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diff --git a/Master/texmf-dist/doc/generic/pgf/version-for-tex4ht/en/pgfmanualse4.html b/Master/texmf-dist/doc/generic/pgf/version-for-tex4ht/en/pgfmanualse4.html deleted file mode 100644 index 0a88c1e8120..00000000000 --- a/Master/texmf-dist/doc/generic/pgf/version-for-tex4ht/en/pgfmanualse4.html +++ /dev/null @@ -1,591 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" - "http://www.w3.org/TR/html4/loose.dtd"> -<html > -<head><title>4 Guidelines on Graphics</title> -<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> -<meta name="generator" content="TeX4ht (http://www.cis.ohio-state.edu/~gurari/TeX4ht/mn.html)"> -<meta name="originator" content="TeX4ht (http://www.cis.ohio-state.edu/~gurari/TeX4ht/mn.html)"> -<!-- html --> -<meta name="src" content="pgfmanual.tex"> -<meta name="date" content="2005-11-15 18:41:00"> -<link rel="stylesheet" type="text/css" href="pgfmanual.css"> -</head><body -> - <div class="crosslinks"><p class="noindent">[<a -href="pgfmanualse5.html" >next</a>] [<a -href="pgfmanualse3.html" >prev</a>] [<a -href="pgfmanualse3.html#tailpgfmanualse3.html" >prev-tail</a>] [<a -href="#tailpgfmanualse4.html">tail</a>] [<a -href="pgfmanual.html#pgfmanualse4.html" >up</a>] </p></div> - <h3 class="sectionHead"><span class="titlemark">4 </span> <a - id="x5-460004"></a>Guidelines on Graphics</h3> -<!--l. 12--><p class="noindent">The present section is not about <span -class="cmcsc-10"><small -class="small-caps">P</small><small -class="small-caps">G</small><small -class="small-caps">F</small></span> or Ti<span -class="cmti-10">k</span>Z, but about general guidelines and principles concerning the creation -of graphics for scientific presentations, papers, and books. -<!--l. 16--><p class="indent"> The guidelines in this section come from different sources. Many of them are just what I would like to claim is -“common sense,” some reflect my personal experience (though, hopefully, not my personal preferences), some come -from books (the bibliography is still missing, sorry) on graphic design and typography. The most influential -source are the brilliant books by Edward Tufte. While I do not agree with everything written in these -books, many of Tufte’s arguments are so convincing that I decided to repeat them in the following -guidelines. -<!--l. 29--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.1 </span> <a - id="x5-470004.1"></a>Should You Follow Guidelines?</h4> -<!--l. 31--><p class="noindent">The first thing you should ask yourself when someone presents a bunch of guidelines is: Should I really follow -these guidelines? This is an important questions, because there are good reasons not to follow general -guidelines. - <ul class="itemize1"> - <li class="itemize">The person who setup the guidelines may have had other objectives than you do. For example, a - guideline might say “use the color red for emphasis.” While this guideline makes perfect sense for, say, - a presentation using a projector, red “color” has the <span -class="cmti-10">opposite </span>effect of “emphasis” when printed using - a black-and-white printer. - <!--l. 44--><p class="noindent">Guidelines were almost always setup to address a specific situation. If you are not in this situation, - following a guideline can do more harm than good. - </li> - <li class="itemize">The basic rule of typography is: “Every rule can be broken, as long as you are <span -class="cmti-10">aware </span>that you are - breaking a rule.” This rule also applies to graphics. Phrased differently, the basic rule states: “The only - mistakes in typography are things done is ignorance.” - <!--l. 54--><p class="noindent">When you are aware of a rule and when you decide that breaking the rule has a desirable effect, break - the rule. - </li> - <li class="itemize">Some guidelines are simply <span -class="cmti-10">wrong</span>, but everyone follows them out of tradition or is forced to do so. - My favorite example is a guideline a software company I used to work for has set in a big project: - All programmers had to declare the parameters of functions in <span -class="cmti-10">increasing order of size</span>. So, one-byte - parameters should come first, then two-byte parameters, and so on. - <!--l. 64--><p class="noindent">This guideline is total nonsense. An (arguably) sensible guideline is “parameters must be declared - alphabetically” so that parameters are easier to find. Another (arguably) sensible guideline is - “parameters must be declared in decreasing order of size” so that less byte-alignment cache misses - occur when the stack is accessed. The guideline the company used maximized cache misses and resulted - in a more or less random ordering so that programmers constantly had to look up the parameter - ordering.</li></ul> -<!--l. 74--><p class="indent"> So, before you apply a guideline or choose not to apply it, ask yourself these questions: - <ol type="1" class="enumerate1" > - <li class="enumerate" value="1" -><a - id="x5-47002x1"></a>Does this guideline really address my situation? - </li> - <li class="enumerate" value="2" -><a - id="x5-47004x2"></a>If you do the opposite a guideline says you should do, will the advantages outweigh the disadvantages - this guideline was supposed to prevent?</li></ol> - - -<!--l. 87--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.2 </span> <a - id="x5-480004.2"></a>Planning the Time Needed for the Creation of Graphics</h4> -<!--l. 89--><p class="noindent">When you create a paper with numerous graphics, the time needed to create these graphics becomes an important -factor. How much time should you calculate for the creation of graphics? -<!--l. 93--><p class="indent"> As a general rule, assume that a graphic will need as much time to create as would a text of the same length. For -example, when I write a paper, I need about one hour per page for the first draft. Later, I need between two and -four hours per page for revisions. Thus, I expect to need about half an hour for the creation of <span -class="cmti-10">a first</span> -<span -class="cmti-10">draft </span>of a half page graphic. Later on, I expect another one to two hours before the final graphic is -finished. -<!--l. 101--><p class="indent"> In many publications, even in good journals, the authors and editors have obviously invested a lot of time on the -text, but seem to have spend about five minutes to create all of the graphics. Graphics often seem to have been -added as an “afterthought” or look like a screen shot of whatever the authors’s statistical software shows them. As -will be argued later on, the graphics that programs like <span -class="cmcsc-10"><small -class="small-caps">G</small><small -class="small-caps">N</small><small -class="small-caps">U</small><small -class="small-caps">P</small><small -class="small-caps">L</small><small -class="small-caps">O</small><small -class="small-caps">T</small> </span>produce by default are of poor -quality. -<!--l. 110--><p class="indent"> Creating informative graphics that help the reader and that fit together with the main text is a difficult, lengthy -process. - <ul class="itemize1"> - <li class="itemize">Treat graphics as first-class citizens of your papers. They deserve as much time and energy as the text - does. - </li> - <li class="itemize">Arguably, the creation of graphics deserves <span -class="cmti-10">even more </span>time than the writing of the main text since - more attention will be paid to the graphics and they will be looked at first. - </li> - <li class="itemize">Plan as much time for the creation and revision of a graphic as you would plan for text of the same - size. - </li> - <li class="itemize">Difficult graphics with a high information density may require even more time. - </li> - <li class="itemize">Very simple graphics will require less time, but most likely you do not want to have “very simple - graphics” in your paper, anyway; just as you would not like to have a “very simple text” of the same - size.</li></ul> -<!--l. 135--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.3 </span> <a - id="x5-490004.3"></a>Workflow for Creating a Graphic</h4> -<!--l. 137--><p class="noindent">When you write a (scientific) paper, you will most likely follow the following pattern: You have some -results/ideas that you would like to report about. The creation of the paper will typically start with -compiling a rough outline. Then, the different sections are filled with text to create a first draft. This -draft is then revised repeatedly until, often after substantial revision, a final paper results. In a good -journal paper there is typically not be a single sentence that has survived unmodified from the first -draft. -<!--l. 146--><p class="indent"> Creating a graphics follows the same pattern: - <ul class="itemize1"> - <li class="itemize">Decide on what the graphic should communicate. Make this a conscious decision, that is, determine - “What is the graphic supposed to tell the reader?” - </li> - <li class="itemize">Create an “outline,” that is, the rough overall “shape” of the graphic, containing the most crucial - elements. Often, it is useful to do this using pencil and paper. - </li> - <li class="itemize">Fill out the finer details of the graphic to create a first draft. - </li> - <li class="itemize">Revise the graphic repeatedly along with the rest of the paper.</li></ul> - - -<!--l. 166--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.4 </span> <a - id="x5-500004.4"></a>Linking Graphics With the Main Text</h4> -<!--l. 168--><p class="noindent">Graphics can be placed at different places in a text. Either, they can be inlined, meaning they are -somewhere “in the middle of the text” or they can be placed in standalone “figures.” Since printers -(the people) like to have their pages “filled,” (both for aesthetic and economic reasons) standalone -figures may traditionally be placed on pages in the document far removed from the main text that -refers to them. <span class="LATEX">L<span class="A">A</span><span class="TEX">T<span -class="E">E</span>X</span></span> and <span class="TEX">T<span -class="E">E</span>X</span> tend to encourage this “drifting away” of graphics for technical -reasons. -<!--l. 177--><p class="indent"> When a graphic is inlined, it will more or less automatically be linked with the main text in the sense that the -labels of the graphic will be implicitly explained by the surrounding text. Also, the main text will typically make it -clear what the graphic is about and what is shown. -<!--l. 183--><p class="indent"> Quite differently, a standalone figure will often be viewed at a time when the main text that this graphic belongs -to either has not yet been read or has been read some time ago. For this reason, you should follow the following -guidelines when creating standalone figures: - <ul class="itemize1"> - <li class="itemize">Standalone figures should have a caption than should make them “understandable by themselves.” - <!--l. 192--><p class="noindent">For example, suppose a graphic shows an example of the different stages of a quicksort algorithm. Then - the figure’s caption should, at the very least, inform the reader that “The figure shows the different - stages of the quicksort algorithm introduced on page xyz.” and not just “Quicksort algorithm.” - </li> - <li class="itemize">A good caption adds as much context information as possible. For example, you could say: “The figure - shows the different stages of the quicksort algorithm introduced on page xyz. In the first line, the pivot - element 5 is chosen. This causes...” While this information can also be given in the main text, putting - it in the caption will ensure that the context is kept. Do not feel afraid of a 5-line caption. (Your editor - may hate you for this. Consider hating them back.) - </li> - <li class="itemize">Reference the graphic in your main text as in “For an example of quicksort ‘in action,’ see Figure 2.1 - on page xyz.” - </li> - <li class="itemize">Most books on style and typography recommend that you do not use abbreviations as in “Fig. 2.1” - but write “Figure 2.1.” - <!--l. 213--><p class="noindent">The main argument against abbreviations is that “a period is too valuable to waste it on an - abbreviation.” The idea is that a period will make the reader assume that the sentence ends after “Fig” - and it takes a “conscious backtracking” to realize that the sentence did not end after all. - <!--l. 219--><p class="noindent">The argument in favor of abbreviations is that they save space. - <!--l. 221--><p class="noindent">Personally, I am not really convinced by either argument. On the one hand, I have not yet seen any - hard evidence that abbreviations slow readers down. On the other hand, abbreviating all “Figure” by - “Fig.” is most unlikely to save even a single line in most documents. - <!--l. 227--><p class="noindent">I avoid abbreviations.</li></ul> -<!--l. 232--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.5 </span> <a - id="x5-510004.5"></a>Consistency Between Graphics and Text</h4> -<!--l. 234--><p class="noindent">Perhaps the most common “mistake” people do when creating graphics (remember that a “mistake” in design is -always just “ignorance”) is to have a mismatch between the way their graphics look and the way their text -looks. -<!--l. 239--><p class="indent"> It is quite common that authors use several different programs for creating the graphics of a paper. An author -might produce some plots using <span -class="cmcsc-10"><small -class="small-caps">G</small><small -class="small-caps">N</small><small -class="small-caps">U</small><small -class="small-caps">P</small><small -class="small-caps">L</small><small -class="small-caps">O</small><small -class="small-caps">T</small></span>, a diagram using <span -class="cmcsc-10"><small -class="small-caps">X</small><small -class="small-caps">F</small><small -class="small-caps">I</small><small -class="small-caps">G</small></span>, and include an <span class="obeylines-h"><span class="verb"><span -class="cmtt-10">.eps</span></span></span> graphic a coauthor -contributed using some unknown program. All these graphics will, most likely, use different line widths, different -fonts, and have different sizes. In addition, authors often use options like <span class="obeylines-h"><span class="verb"><span -class="cmtt-10">[height=5cm]</span></span></span> when including graphics to -scale them to some “nice size.” - - -<!--l. 248--><p class="indent"> If the same approach were taken to writing the main text, every section would be written in a different font at a -different size. In some sections all theorems would be underlined, in another they would be printed -all in uppercase letters, and in another in red. In addition, the margins would be different on each -page. -<!--l. 254--><p class="indent"> Readers and editors would not tolerate a text if it were written in this fashion, but with graphics they often have -to. -<!--l. 257--><p class="indent"> To create consistency between graphics and text, stick to the following guidelines: - <ul class="itemize1"> - <li class="itemize">Do not scale graphics. - <!--l. 263--><p class="noindent">This means that when generating graphics using an external program, create them “at the right size.” - </li> - <li class="itemize">Use the same font(s) both in graphics and the body text. - </li> - <li class="itemize">Use the same line width in text and graphics. - <!--l. 270--><p class="noindent">The “line width” for normal text is the width of the stem of letters like T. For <span class="TEX">T<span -class="E">E</span>X</span>, this is usually - 0<span -class="cmmi-10">.</span>4pt. However, some journals will not accept graphics with a normal line width below 0<span -class="cmmi-10">.</span>5pt. - </li> - <li class="itemize">When using colors, use a consistent color coding in the text and in graphics. For example, if red is - supposed to alert the reader to something in the main text, use red also in graphics for important parts - of the graphic. If blue is used for structural elements like headlines and section titles, use blue also for - structural elements of your graphic. - <!--l. 282--><p class="noindent">However, graphics may also use a logical intrinsic color coding. For example, no matter what colors - you normally use, readers will generally assume, say, that the color green as “positive, go, ok” and red - as “alert, warning, action.”</li></ul> -<!--l. 288--><p class="indent"> Creating consistency when using different graphic programs is almost impossible. For this reason, you should -consider sticking to a single graphic program. -<!--l. 293--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.6 </span> <a - id="x5-520004.6"></a>Labels in Graphics</h4> -<!--l. 295--><p class="noindent">Almost all graphics will contain labels, that is, pieces of text that explain parts of the graphics. When placing labels, -stick to the following guidelines: - <ul class="itemize1"> - <li class="itemize">Follow the rule of consistency when placing labels. You should do so in two ways: First, be consistent - with the main text, that is, use the same font as the main text also for labels. Second, be consistent - between labels, that is, if you format some labels in some particular way, format all labels in this way. - </li> - <li class="itemize">In addition to using the same fonts in text and graphics, you should also use the same notation. For - example, if you write 1<span -class="cmmi-10">/</span>2 in your main text, also use “1<span -class="cmmi-10">/</span>2” as labels in graphics, not “0.5”. A <span -class="cmmi-10"><img -src="cmmi10-19.png" alt="p" class="10x-x-19" /> </span>is a - “<span -class="cmmi-10"><img -src="cmmi10-19.png" alt="p" class="10x-x-19" /></span>” and not “3<span -class="cmmi-10">.</span>141”. Finally, e<sup ><span -class="cmsy-7">-</span><span -class="cmr-7">i</span><span -class="cmmi-7"><img -src="cmmi7-19.png" alt="p" class="7x-x-19" /></span></sup> is “e<sup ><span -class="cmsy-7">-</span><span -class="cmr-7">i</span><span -class="cmmi-7"><img -src="cmmi7-19.png" alt="p" class="7x-x-19" /></span></sup>”, not “<span -class="cmsy-10">-</span>1”, let alone “-1”. - </li> - <li class="itemize">Labels should be legible. They should not only have a reasonably large size, they also should not be - obscured by lines or other text. This also applies to of lines and text <span -class="cmti-10">behind </span>the labels. - </li> - <li class="itemize">Labels should be “in place.” Whenever there is enough space, labels should be placed next to the - thing they label. Only if necessary, add a (subdued) line from the label to the labeled object. Try to - avoid labels that only reference explanations in external legends. Reader have to jump back and forth - between the explanation and the object that is described. - </li> - <li class="itemize">Consider subduing “unimportant” labels using, for example, a gray color. This will keep the focus on - the actual graphic.</li></ul> - - -<!--l. 332--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.7 </span> <a - id="x5-530004.7"></a>Plots and Charts</h4> -<!--l. 334--><p class="noindent">One of the most frequent kind of graphics, especially in scientific papers, are <span -class="cmti-10">plots</span>. They come in a large -variety, including simple line plots, parametric plots, three dimensional plots, pie charts, and many -more. -<!--l. 339--><p class="indent"> Unfortunately, plots are notoriously hard to get right. Partly, the default settings of programs like -<span -class="cmcsc-10"><small -class="small-caps">G</small><small -class="small-caps">N</small><small -class="small-caps">U</small><small -class="small-caps">P</small><small -class="small-caps">L</small><small -class="small-caps">O</small><small -class="small-caps">T</small> </span>or Excel are to blame for this since these programs make it very convenient to create bad -plots. -<!--l. 344--><p class="indent"> The first question you should ask yourself when creating a plot is the following: - <ul class="itemize1"> - <li class="itemize">Are there enough data points to merit a plot?</li></ul> -<!--l. 351--><p class="indent"> If the answer is “not really,” use a table. -<!--l. 353--><p class="indent"> A typical situation where a plot is unnecessary is when people present a few numbers in a bar diagram. Here is a -real-life example: At the end of a seminar a lecturer asked the participants for feedback. Of the 50 participants, 30 -returned the feedback form. According to the feedback, three participants considered the seminar “very good,” -nine considered it “good,” ten “ok,” eight “bad,” and no one thought that the seminar was “very -bad.” -<!--l. 361--><p class="indent"> A simple way of summing up this information is the following table: - <div class="tabular"><table class="tabular" -cellspacing="0" cellpadding="0" -frame="void" id="TBL-63-" ><colgroup id="TBL-63-1g"><col -id="TBL-63-1"><col -id="TBL-63-2"><col -id="TBL-63-3"></colgroup><tr - valign="baseline" id="TBL-63-1-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-1-1" -class="td11"> <span -class="cmti-10">Rating given </span></td><td align="left" id="TBL-63-1-2" -class="td11"> <!--l. 365--><p class="noindent"><span -class="cmti-10">Participants</span> - <span -class="cmti-10">(out</span> - <span -class="cmti-10">of</span> - <span -class="cmti-10">50)</span> - <span -class="cmti-10">who</span> - <span -class="cmti-10">gave</span> - <span -class="cmti-10">this</span> - <span -class="cmti-10">rating</span> </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-1-3" -class="td11"> <span -class="cmti-10">Percentage </span></td> -</tr><tr -class="vspace" style="font-size:17.50002pt"><td -> </td><td -> </td><td -> </td></tr><tr - valign="baseline" id="TBL-63-2-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-2-1" -class="td11"> “very good” </td><td align="left" id="TBL-63-2-2" -class="td11"> <!--l. 367--><p class="noindent"> 3 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-2-3" -class="td11"> 6% </td> -</tr><tr - valign="baseline" id="TBL-63-3-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-3-1" -class="td11"> “good” </td><td align="left" id="TBL-63-3-2" -class="td11"> <!--l. 368--><p class="noindent"> 9 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-3-3" -class="td11"> 18% </td> -</tr><tr - valign="baseline" id="TBL-63-4-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-4-1" -class="td11"> “ok” </td><td align="left" id="TBL-63-4-2" -class="td11"> <!--l. 369--><p class="noindent"> 10 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-4-3" -class="td11"> 20% </td> -</tr><tr - valign="baseline" id="TBL-63-5-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-5-1" -class="td11"> “bad” </td><td align="left" id="TBL-63-5-2" -class="td11"> <!--l. 370--><p class="noindent"> 8 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-5-3" -class="td11"> 16% </td> -</tr><tr - valign="baseline" id="TBL-63-6-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-6-1" -class="td11"> “very bad” </td><td align="left" id="TBL-63-6-2" -class="td11"> <!--l. 371--><p class="noindent"> 0 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-6-3" -class="td11"> 0% </td> -</tr><tr -class="vspace" style="font-size:5.69054pt"><td -> </td><td -> </td><td -> </td></tr><tr - valign="baseline" id="TBL-63-7-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-7-1" -class="td11"> none </td><td align="left" id="TBL-63-7-2" -class="td11"> <!--l. 372--><p class="noindent"> 20 </td><td align="right" style="white-space:nowrap; text-align:right;" id="TBL-63-7-3" -class="td11"> 40% </td> -</tr><tr - valign="baseline" id="TBL-63-8-"><td align="left" style="white-space:nowrap; text-align:left;" id="TBL-63-8-1" -class="td11"> </td> </tr></table> -</div> -<!--l. 376--><p class="indent"> What the lecturer did was to visualize the data using a 3D bar diagram. It looked like this: -<!--l. 400--><p class="indent"> <object data="pgfmanual-60.svg" width="269.42331 " height="193.05234 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object> -<!--l. 403--><p class="indent"> Both the table and the “plot” have about the same size. If your first thought is “the graphic looks nicer -than the table,” try to answer the following questions based on the information in the table or in the -graphic: - - - <ol type="1" class="enumerate1" > - <li class="enumerate" value="1" -><a - id="x5-53002x1"></a>How many participants where there? - </li> - <li class="enumerate" value="2" -><a - id="x5-53004x2"></a>How many participants returned the feedback form? - </li> - <li class="enumerate" value="3" -><a - id="x5-53006x3"></a>What percentage of the participants returned the feedback form? - </li> - <li class="enumerate" value="4" -><a - id="x5-53008x4"></a>How many participants checked “very good”? - </li> - <li class="enumerate" value="5" -><a - id="x5-53010x5"></a>What percentage out of all participants checked “very good”? - </li> - <li class="enumerate" value="6" -><a - id="x5-53012x6"></a>Did more than a quarter of the participants check “bad” or “very bad”? - </li> - <li class="enumerate" value="7" -><a - id="x5-53014x7"></a>What percentage of the participants that returned the form checked “very good”?</li></ol> -<!--l. 424--><p class="indent"> Sadly, the graphic does not allow us to answer <span -class="cmti-10">a single one of these questions</span>. The table answers all of them -directly, except for the last one. In essence, the information density of the graphic is very nearly zero. The table has -a much higher information density; despite the fact that it uses quite a lot of white space to present a few -numbers. -<!--l. 430--><p class="indent"> Here is the list of things that went wrong with the 3D-bar diagram: - <ul class="itemize1"> - <li class="itemize">The whole graphic is dominated by irritating background lines. - </li> - <li class="itemize">It is not clear what the numbers at the left mean; presumably percentages, but it might also be the - absolute number of participants. - </li> - <li class="itemize">The labels at the bottom are rotated, making them hard to read. - <!--l. 441--><p class="noindent">(In the real presentation that I saw, the text was rendered at a very low resolution with about 10 by - 6 pixels per letter with wrong kerning, making the rotated text almost impossible to read.) - </li> - <li class="itemize">The third dimension adds complexity to the graphic without adding information. - </li> - <li class="itemize">The three dimensional setup makes it much harder to gauge the height of the bars correctly. Consider - the “bad” bar. It the number this bar stands for more than 20 or less? While the front of the bar is - below the 20 line, the back of the bar (which counts) is above. - </li> - <li class="itemize">It is impossible to tell which numbers are represented by the bars. Thus, the bars needlessly hide the - information these bars are all about. - </li> - <li class="itemize">What do the bar heights add up to? Is it 100% or 60%? - </li> - <li class="itemize">Does the bar for “very bad” represent 0 or 1? - </li> - <li class="itemize">Why are the bars blue?</li></ul> -<!--l. 464--><p class="indent"> You might argue that in the example the exact numbers are not important for the graphic. The important things -is the “message,” which is that there are more “very good” and “good” ratings than “bad” and “very bad.” -However, to convey this message either use a sentence that says so or use a graphic that conveys this message more -clearly: - - -<!--l. 503--><p class="indent"> <object data="pgfmanual-61.svg" width="424.91754 " height="224.69525 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object> -<!--l. 506--><p class="indent"> The above graphic has about the same information density as the table (about the same size and the same -numbers are shown). In addition, one can directly “see” that there are more good or very good ratings than bad -ones. One can also “see” that the number of people who gave no rating at all is not negligible, which is quite -common for feedback forms. -<!--l. 513--><p class="indent"> Charts are not always a good idea. Let us look at an example that I redrew from a pie chart in <span -class="cmti-10">Die Zeit</span>, June -4th, 2005: -<!--l. 606--><p class="indent"> <object data="pgfmanual-62.svg" width="595.82195 " height="237.71802 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object> -<!--l. 608--><p class="indent"> This graphic has been redrawn in Ti<span -class="cmti-10">k</span>Z, but the original looks very similar. -<!--l. 611--><p class="indent"> At first sight, the graphic looks “nice and informative,” but there are a lot of things that went -wrong: - <ul class="itemize1"> - <li class="itemize">The chart is three dimensional. However, the shadings add nothing “information-wise,” at best, they - distract. - </li> - <li class="itemize">In a 3D-pie-chart the relative sizes are very strongly distorted. For example, the area taken up by the - gray color of “Braunkohle” is larger than the area taken up by the green color of “Kernenergie” <span -class="cmti-10">despite</span> - <span -class="cmti-10">the fact that the percentage of Braunkohle is less than the percentage of Kernenergie</span>. - </li> - <li class="itemize">The 3D-distortion gets worse for small areas. The area of “Regenerative” somewhat larger than the - area of “Erdgas.” The area of “Wind” is slightly smaller than the area of “Mineralölprodukte” <span -class="cmti-10">although</span> - <span -class="cmti-10">the percentage of Wind is nearly three times larger than the percentage of Mineral</span><span -class="cmti-10">ölprodukte.</span> - - - <!--l. 632--><p class="noindent">In the last case, the different sizes are only partly due to distortion. The designer(s) of the original - graphic have also made the “Wind” slice too small, even taking distortion into account. (Just compare - the size of “Wind” to “Regenerative” in general.) - </li> - <li class="itemize">According to its caption, this chart is supposed to inform us that coal was the most important energy - source in Germany in 2004. Ignoring the strong distortions caused by the superfluous and misleading - 3D-setup, it takes quite a while for this message to get across. - <!--l. 644--><p class="noindent">Coal as an energy source is split up into two slices: one for “Steinkohle” and one for “Braunkohle” (two - different kinds of coal). When you add them up, you see that the whole lower half of the pie chart is - taken up by coal. - <!--l. 649--><p class="noindent">The two areas for the different kinds of coal are not visually linked at all. Rather, two different colors - are used, the labels are on different sides of the graphic. By comparison, “Regenerative” and “Wind” - are very closely linked. - </li> - <li class="itemize">The color coding of the graphic follows no logical pattern at all. Why is nuclear energy green? - Regenerative energy is light blue, “other sources” are blue. It seems more like a joke that the area for - “Braunkohle” (which literally translates to “brown coal”) is stone gray, while the area for “Steinkohle” - (which literally translates to “stone coal”) is brown. - </li> - <li class="itemize">The area with the lightest color is used for “Erdgas.” This area stands out most because of the brighter - color. However, for this chart “Erdgas” is not really important at all.</li></ul> -<!--l. 665--><p class="noindent">Edward Tufte calls graphics like the above “chart junk.” -<!--l. 667--><p class="indent"> Here are a few recommendations that may help you avoid producing chart junk: - <ul class="itemize1"> - <li class="itemize">Do not use 3D pie charts. They are <span -class="cmti-10">evil</span>. - </li> - <li class="itemize">Consider using a table instead of a pie chart. - </li> - <li class="itemize">Due not apply colors randomly; use them to direct the readers’s focus and to group things. - </li> - <li class="itemize">Do not use background patterns, like a crosshatch or diagonal lines, instead of colors. They distract. - Background patterns in information graphics are <span -class="cmti-10">evil</span>.</li></ul> -<!--l. 684--><p class="noindent"> - <h4 class="subsectionHead"><span class="titlemark">4.8 </span> <a - id="x5-540004.8"></a>Attention and Distraction</h4> -<!--l. 686--><p class="noindent">Pick up your favorite fiction novel and have a look at a typical page. You will notice that the page is very uniform. -Nothing is there to distract the reader while reading; no large headlines, no bold text, no large white areas. Indeed, -even when the author does wish to emphasize something, this is done using italic letters. Such letters blend nicely -with the main text--at a distance you will not be able to tell whether a page contains italic letters, but you would -notice a single bold word immediately. The reason novels are typeset this way is the following paradigm: Avoid -distractions. -<!--l. 696--><p class="indent"> Good typography (like good organization) is something you do <span -class="cmti-10">not </span>notice. The job of typography is to make -reading the text, that is, “absorbing” its information content, as effortless as possible. For a novel, readers absorb -the content by reading the text line-by-line, as if they were listening to someone telling the story. In this situation -anything on the page that distracts the eye from going quickly and evenly from line to line will make the text harder -to read. -<!--l. 705--><p class="indent"> Now, pick up your favorite weekly magazine or newspaper and have a look at a typical page. You will notice that -there is quite a lot “going on” on the page. Fonts are used at different sizes and in different arrangements, the text is -organized in narrow columns, typically interleaved with pictures. The reason magazines are typeset in this way is -another paradigm: Steer attention. - - -<!--l. 713--><p class="indent"> Readers will not read a magazine like a novel. Instead of reading a magazine line-by-line, we use headlines and -short abstracts to check whether we want to read a certain article or not. The job of typography is to steer our -attention to these abstracts and headlines, first. Once we have decided that we want to read an article, however, we -no longer tolerate distractions, which is why the main text of articles is typeset exactly the same way as a -novel. -<!--l. 721--><p class="indent"> The two principles “avoid distractions” and “steer attention” also apply to graphics. When you design a graphic, -you should eliminate everything that will “distract the eye.” At the same time, you should try to -actively help the reader “through the graphic” by using fonts/colors/line widths to highlight different -parts. -<!--l. 727--><p class="indent"> Here is a non-exhaustive list of things that can distract readers: - <ul class="itemize1"> - <li class="itemize">Strong contrasts will always be registered first by the eye. For example, consider the following two - grids: - <!--l. 737--><p class="noindent"><object data="pgfmanual-63.svg" width="161.5327 " height="54.86644 " type="image/svg+xml"><p>SVG-Viewer needed.</p></object> - <!--l. 740--><p class="noindent">Even though the left grid comes first in our normal reading order, the right one is much more likely to be seen - first: The white-to-black contrast is higher than the gray-to-white contrast. In addition, there are more - “places” adding to the overall contrast in the right grid. - <!--l. 746--><p class="noindent">Things like grids and, more generally, help lines usually should not grab the attention of the readers and, - hence, should be typeset with a low contrast to the background. Also, a loosely-spaced grid is less distracting - than a very closely-spaced grid. - </li> - <li class="itemize">Dashed lines create many points at which there is black-to-white contrast. Dashed or dotted lines can be very - distracting and, hence, should be avoided in general. - <!--l. 755--><p class="noindent">Do not use different dashing patterns to differentiate curves in plots. You loose data points this way and the - eye is not particularly good at “grouping things according to a dashing pattern.” The eye is <span -class="cmti-10">much </span>better at - grouping things according to colors. - </li> - <li class="itemize">Background patterns filling an area using diagonal lines or horizontal and vertical lines or just dots are almost - always distracting and, usually, serve no real purpose. - </li> - <li class="itemize">Background images and shadings distract and only seldom add anything of importance to a - graphic. - </li> - <li class="itemize">Cute little cliparts can easily draw attention away from the data.</li></ul> - - - - - - - <div class="crosslinks"><p class="noindent">[<a -href="pgfmanualse5.html" >next</a>] [<a -href="pgfmanualse3.html" >prev</a>] [<a -href="pgfmanualse3.html#tailpgfmanualse3.html" >prev-tail</a>] [<a -href="pgfmanualse4.html" >front</a>] [<a -href="pgfmanual.html#pgfmanualse4.html" >up</a>] </p></div> -<!--l. 8--><p class="indent"> <a - id="tailpgfmanualse4.html"></a> -</body></html> |