summaryrefslogtreecommitdiff
path: root/graphics/pgf/base/doc/text-en/pgfmanual-en-library-plot-handlers.tex
blob: 689e3f0c1bf8b09844170fa4be583d1ca094a843 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
% Copyright 2018 by Till Tantau
%
% This file may be distributed and/or modified
%
% 1. under the LaTeX Project Public License and/or
% 2. under the GNU Free Documentation License.
%
% See the file doc/generic/pgf/licenses/LICENSE for more details.


\section{Plot Handler Library}
\label{section-library-plothandlers}

\begin{pgflibrary}{plothandlers}
    This library packages defines additional plot handlers, see
    Section~\ref{section-plot-handlers} for an introduction to plot handlers.
    The additional handlers are described in the following.

    This library is loaded automatically by \tikzname.
\end{pgflibrary}


\subsection{Curve Plot Handlers}

\begin{command}{\pgfplothandlercurveto}
    This handler will issue a |\pgfpathcurveto| command for each point of the
    plot, \emph{except} possibly for the first. As for the line-to handler,
    what happens with the first point can be specified using
    |\pgfsetmovetofirstplotpoint| or |\pgfsetlinetofirstplotpoint|.

    Obviously, the |\pgfpathcurveto| command needs, in addition to the points
    on the path, some control points. These are generated automatically using a
    somewhat ``dumb'' algorithm: Suppose you have three points $x$, $y$, and
    $z$ on the curve such that $y$ is between $x$ and $z$:
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlercurveto
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}

    In order to determine the control points of the curve at the point $y$, the
    handler computes the vector $z-x$ and scales it by the tension factor (see
    below). Let us call the resulting vector $s$. Then $y+s$ and $y-s$ will be
    the control points around $y$. The first control point at the beginning of
    the curve will be the beginning itself, once more; likewise the last
    control point is the end itself.
\end{command}

\begin{command}{\pgfsetplottension\marg{value}}
    Sets the factor used by the curve plot handlers to determine the distance
    of the control points from the points they control. The higher the
    curvature of the curve points, the higher this value should be. A value of
    $1$ will cause four points at quarter positions of a circle to be connected
    using a circle. The default is $0.5$.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfsetplottension{0.75}
  \pgfplothandlercurveto
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerclosedcurve}
    This handler works like the curve-to plot handler, only it will add a new
    part to the current path that is a closed curve through the plot points.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerclosedcurve
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}


\subsection{Constant Plot Handlers}

There are several plot handlers which produce piecewise constant interpolations
between successive points:

\begin{command}{\pgfplothandlerconstantlineto}
    This handler works like the line-to plot handler, only it will produce a
    connected, piecewise constant path to connect the points.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerconstantlineto
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerconstantlinetomarkright}
    A variant of |\pgfplothandlerconstantlineto| which places its mark on the
    right line ends.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerconstantlinetomarkright
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerconstantlinetomarkmid}
    A variant of |\pgfplothandlerconstantlineto| which places its mark on the
    center of the line.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerconstantlinetomarkmid
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
    The plot handler always connects two data points by a horizontal line
    starting from the previous data points, followed by a vertical line in the
    middle between the two data points, followed by a horizontal line between
    the middle and the current data point. This results in a symmetric constant
    plot handler for constant mesh width.
\end{command}

\begin{command}{\pgfplothandlerjumpmarkleft}
    This handler works like the line-to plot handler, only it will produce a
    non-connected, piecewise constant path to connect the points. If there are
    any plot marks, they will be placed on the left open pieces.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerjumpmarkleft
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerjumpmarkright}
    This handler works like the line-to plot handler, only it will produce a
    non-connected, piecewise constant path to connect the points. If there are
    any plot marks, they will be placed on the right open pieces.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerjumpmarkright
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerjumpmarkmid}
    This handler works like the |\pgfplothandlerconstantlinetomarkmid|, but it
    will produce a non-connected, piecewise constant path to connect the
    points. If there are any plot marks, they will be placed in the center of
    the horizontal line segment..
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerjumpmarkmid
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
    See |\pgfplothandlerconstantlinetomarkmid| for details.
\end{command}


\subsection{Comb Plot Handlers}

There are three ``comb'' plot handlers. Their name stems from the fact that the
plots they produce look like ``combs'' (more or less).

\begin{command}{\pgfplothandlerxcomb}
    This handler converts each point in the plot stream into a line from the
    $y$-axis to the point's coordinate, resulting in a ``horizontal comb''.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerxcomb
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerycomb}
    This handler converts each point in the plot stream into a line from the
    $x$-axis to the point's coordinate, resulting in a ``vertical comb''.

    This handler is useful for creating ``bar diagrams''.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerycomb
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerpolarcomb}
    This handler converts each point in the plot stream into a line from the
    origin to the point's coordinate.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerpolarcomb
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\pgfname\ bar or comb plots usually draw something from zero to the current
plot's coordinate. The ``zero'' offset can be changed using an input stream
which returns the desired offset successively for each processed coordinate.

There are two such streams, which can be configured independently. The first
one returns ``zeros'' for coordinate~$x$, the second one returns ``zeros'' for
coordinate~$y$. They are used as follows.
%
\begin{codeexample}[code only]
\pgfplotxzerolevelstreamstart
\pgfplotxzerolevelstreamnext % assigns \pgf@x
\pgfplotxzerolevelstreamnext
\pgfplotxzerolevelstreamnext
\pgfplotxzerolevelstreamend
\end{codeexample}
%
\begin{codeexample}[code only]
\pgfplotyzerolevelstreamstart
\pgfplotyzerolevelstreamnext % assigns \pgf@x
\pgfplotyzerolevelstreamend
\end{codeexample}
%
Different zero level streams can be implemented by overwriting these macros.

\begin{command}{\pgfplotxzerolevelstreamconstant\marg{dimension}}
    This zero level stream always returns \marg{dimension} instead of $x=0$pt.

    It is used for |xcomb| and |xbar|.
\end{command}

\begin{command}{\pgfplotyzerolevelstreamconstant\marg{dimension}}
    This zero level stream always returns \marg{dimension} instead of $y=0$pt.

    It is used for |ycomb| and |ybar|.
\end{command}


\subsection{Bar Plot Handlers}
\label{section-plotlib-bar-handlers}

While comb plot handlers produce a line-to operation to generate combs, bar
plot handlers employ rectangular shapes, allowing filled bars (or pattern
bars).

\begin{command}{\pgfplothandlerybar}
    This handler converts each point in the plot stream into a rectangle from
    the $x$-axis to the point's coordinate. The rectangle is placed centered at
    the $x$-axis.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerybar
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlerxbar}
    This handler converts each point in the plot stream into a rectangle from
    the $y$-axis to the point's coordinate. The rectangle is placed centered at
    the $y$-axis.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlerxbar
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\label{key-bar-width}%
\begin{key}{/pgf/bar width=\marg{dimension} (initially 10pt)}
\keyalias{tikz}
    Sets the width of |\pgfplothandlerxbar| and |\pgfplothandlerybar| to
    \marg{dimension}. The argument \marg{dimension} will be evaluated using the
    math parser.
\end{key}

\label{key-bar-shift}%
\begin{key}{/pgf/bar shift=\marg{dimension} (initially 0pt)}
\keyalias{tikz}
    Sets a shift used by |\pgfplothandlerxbar| and |\pgfplothandlerybar| to
    \marg{dimension}. It has the same effect as |xshift|, but it applies only
    to those bar plots. The argument \marg{dimension} will be evaluated using
    the math parser.
\end{key}

\begin{command}{\pgfplotbarwidth}
    Expands to the value of |/pgf/bar width|.
\end{command}

\begin{command}{\pgfplothandlerybarinterval}
    This handler is a variant of |\pgfplothandlerybar| which works with
    intervals instead of points.

    Bars are drawn between successive input coordinates and the width is
    determined relatively to the interval length.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,2) node {$x_1$} (1,1) node {$x_2$} (2,.5) node {$x_3$} (4,0.7) node {$x_4$};
  \pgfplothandlerybarinterval
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{2cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreampoint{\pgfpoint{4cm}{0.7cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}

    In more detail, if $(x_i,y_i)$ and $(x_{i+1},y_{i+1})$ denote successive
    input coordinates, the bar will be placed above the interval
    $[x_i,x_{i+1}]$, centered at
    %
        \[ x_i + \text{\meta{bar interval shift}} \cdot (x_{i+1} - x_i) \]
    %
    with width
    %
        \[ \text{\meta{bar interval width}} \cdot (x_{i+1} - x_i). \]
    %
    Here, \meta{bar interval shift} and \meta{bar interval width} denote the
    current values of the associated options.

    If you have $N+1$ input points, you will get $N$ bars (one for each
    interval). The $y$~value of the last point will be ignored.
\end{command}

\begin{command}{\pgfplothandlerxbarinterval}
    As |\pgfplothandlerybarinterval|, this handler provides bar plots with
    relative bar sizes and offsets, one bar for each $y$~coordinate interval.
\end{command}

\begin{key}{/pgf/bar interval shift=\marg{factor} (initially 0.5)}
\label{key-bar-interval-shift}%
\keyalias{tikz}
    Sets the \emph{relative} shift of |\pgfplothandlerxbarinterval| and
    |\pgfplothandlerybarinterval| to \meta{factor}. As
    |/pgf/bar interval width|, the argument is relative to the interval length
    of the input coordinates.

    The argument \marg{scale} will be evaluated using the math parser.
\end{key}

\begin{key}{/pgf/bar interval width=\marg{scale} (initially 1)}
\label{key-bar-interval-width}%
\keyalias{tikz}
    Sets the \emph{relative} width of |\pgfplothandlerxbarinterval| and
    |\pgfplothandlerybarinterval| to \marg{scale}. The argument is relative to
    $(x_{i+1} - x_i)$ for $y$~bar plots and relative to $(y_{i+1}-y_i)$ for
    $x$~bar plots.

    The argument \marg{scale} will be evaluated using the math parser.
    %
\begin{codeexample}[]
\begin{tikzpicture}[bar interval width=0.5]
  \draw[gray]
    (0,3) -- (0,-0.1)
    (1,3) -- (1,-0.1)
    (2,3) -- (2,-0.1)
    (4,3) -- (4,-0.1);
  \pgfplothandlerybarinterval
  \begin{scope}[bar interval shift=0.25,fill=blue]
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{2cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreampoint{\pgfpoint{4cm}{0.7cm}}
  \pgfplotstreamend
  \pgfusepath{fill}
  \end{scope}
  \begin{scope}[bar interval shift=0.75,fill=red]
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{3cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{0.2cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.7cm}}
  \pgfplotstreampoint{\pgfpoint{4cm}{0.2cm}}
  \pgfplotstreamend
  \pgfusepath{fill}
  \end{scope}
\end{tikzpicture}
\end{codeexample}
    %
    Please note that bars are always centered, so we have to use shifts $0.25$
    and $0.75$ instead of $0$ and $0.5$.
\end{key}


\subsection{Gapped Plot Handlers}
\label{section-plot-gapped}

\begin{command}{\pgfplothandlergaplineto}
    This handler will connect the points of the plots by straight line
    segments. However, at the start and the end of the lines there will be a
    small gap, given by the following key:
    %
    \begin{key}{/pgf/gap around stream point=\meta{dimension} (initially 1.5pt)}
        The \meta{dimension} by which the lines between consecutive stream
        points are shortened at the beginning and end.
    \end{key}
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \pgfplothandlergaplineto
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfplothandlergapcycle}
    Works like |\pgfplothandlergaplineto|, but the last point is connected to
    the first in the same fashion:
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \pgfplothandlergapcycle
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}


\subsection{Mark Plot Handler}
\label{section-plot-marks}

\begin{command}{\pgfplothandlermark\marg{mark code}}
    This command will execute the \meta{mark code} for some points of the plot,
    but each time the coordinate transformation matrix will be set up such that
    the origin is at the position of the point to be plotted. This way, if the
    \meta{mark code} draws a little circle around the origin, little circles
    will be drawn at some point of the plot.

    By default, a mark is drawn at all points of the plot. However, two
    parameters $r$ and $p$ influence this. First, only every $r$th mark is
    drawn. Second, the first mark drawn is the $p$th. These parameters can be
    influenced using the commands below.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlermark{\pgfpathcircle{\pgfpointorigin}{4pt}\pgfusepath{stroke}}
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}

    Typically, the \meta{code} will be |\pgfuseplotmark{|\meta{plot mark
    name}|}|, where \meta{plot mark name} is the name of a predefined plot
    mark.
\end{command}

\begin{command}{\pgfsetplotmarkrepeat\marg{repeat}}
    Sets the $r$ parameter to \meta{repeat}, that is, only every $r$th mark
    will be drawn.
\end{command}

\begin{command}{\pgfsetplotmarkphase\marg{phase}}
    Sets the $p$ parameter to \meta{phase}, that is, the first mark to be drawn
    is the $p$th, followed by the $(p+r)$th, then the $(p+2r)$th, and so on.
\end{command}

\begin{command}{\pgfplothandlermarklisted\marg{mark code}\marg{index list}}
    This command works similar to the previous one. However, marks will only be
    placed at those indices in the given \meta{index list}. The syntax for the
    list is the same as for the |\foreach| statement. For example, if you
    provide the list |1,3,...,25|, a mark will be placed only at every second
    point. Similarly, |1,2,4,8,16,32| yields marks only at those points that
    are powers of two.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlermarklisted
    {\pgfpathcircle{\pgfpointorigin}{4pt}\pgfusepath{stroke}}
    {1,3}
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfuseplotmark\marg{plot mark name}}
    Draws the given \meta{plot mark name} at the origin. The \meta{plot mark
    name} must have been previously declared using |\pgfdeclareplotmark|.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlermark{\pgfuseplotmark{pentagon}}
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfdeclareplotmark\marg{plot mark name}\marg{code}}
    Declares a plot mark for later used with the |\pgfuseplotmark| command.
    %
\begin{codeexample}[]
\pgfdeclareplotmark{my plot mark}
  {\pgfpathcircle{\pgfpoint{0cm}{1ex}}{1ex}\pgfusepathqstroke}
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfplothandlermark{\pgfuseplotmark{my plot mark}}
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{command}{\pgfsetplotmarksize\marg{dimension}}
    This command sets the \TeX\ dimension |\pgfplotmarksize| to
    \meta{dimension}. This dimension is a ``recommendation'' for plot mark code
    at which size the plot mark should be drawn; plot mark code may choose to
    ignore this \meta{dimension} altogether. For circles, \meta{dimension}
    should  be the radius, for other shapes it should be about half the
    width/height.

    The predefined plot marks all take this dimension into account.
    %
\begin{codeexample}[]
\begin{tikzpicture}
  \draw[gray] (0,0) node {x} (1,1) node {y} (2,.5) node {z};
  \pgfsetplotmarksize{1ex}
  \pgfplothandlermark{\pgfuseplotmark{*}}
  \pgfplotstreamstart
  \pgfplotstreampoint{\pgfpoint{0cm}{0cm}}
  \pgfplotstreampoint{\pgfpoint{1cm}{1cm}}
  \pgfplotstreampoint{\pgfpoint{2cm}{0.5cm}}
  \pgfplotstreamend
  \pgfusepath{stroke}
\end{tikzpicture}
\end{codeexample}
    %
\end{command}

\begin{textoken}{\pgfplotmarksize}
    A \TeX\ dimension that is a ``recommendation'' for the size of plot marks.
\end{textoken}

The following plot marks are predefined (the filling color has been set to
yellow):

\medskip
\begin{tabular}{lc}
    \plotmarkentry{*}
    \plotmarkentry{x}
    \plotmarkentry{+}
\end{tabular}


%%% Local Variables:
%%% mode: latex
%%% TeX-master: "pgfmanual-pdftex-version"
%%% End: