1PLCONT(3plplot) PLplot API PLCONT(3plplot)
2
6 plcont - Contour plot
7
9 plcont(f, nx, ny, kx, lx, ky, ly, clevel, nlevel, pltr, pltr_data)
10
12 Draws a contour plot of the data in f[nx][ny], using the nlevel contour
13 levels specified by clevel. Only the region of the matrix from kx to lx
14 and from ky to ly is plotted out where all these index ranges are in‐
15 terpreted as one-based for historical reasons. A transformation rou‐
16 tine pointed to by pltr with a generic pointer pltr_data for additional
17 data required by the transformation routine is used to map indices
18 within the matrix to the world coordinates.
19 Redacted form: plcont(f, kx, lx, ky, ly, clevel, pltr, pltr_data) where
21 (see above discussion) the pltr, pltr_data callback arguments are some‐
22 times replaced by a tr vector with 6 elements; xg and yg vectors; or xg
23 and yg matrices.
24 This function is used in examples 9, 14, 16, and 22.
26
28 f (PLFLT_MATRIX(3plplot), input)
29 A matrix containing data to be contoured.
30 nx, ny (PLINT(3plplot), input)
32 The dimensions of the matrix f.
33 kx, lx (PLINT(3plplot), input)
35 Range of x indices to consider where 0 <= kx-1 < lx-1 < nx.
36 Values of kx and lx are one-based rather than zero-based for
37 historical backwards-compatibility reasons.
38 ky, ly (PLINT(3plplot), input)
40 Range of y indices to consider where 0 <= ky-1 < ly-1 < ny.
41 Values of ky and ly are one-based rather than zero-based for
42 historical backwards-compatibility reasons.
43 clevel (PLFLT_VECTOR(3plplot), input)
45 A vector specifying the levels at which to draw contours.
46 nlevel (PLINT(3plplot), input)
48 Number of contour levels to draw.
49 pltr (PLTRANSFORM_callback(3plplot), input)
51 A callback function that defines the transformation between the
52 zero-based indices of the matrix f and the world coordinates.For
53 the C case, transformation functions are provided in the PLplot
54 library: pltr0(3plplot) for the identity mapping, and
55 pltr1(3plplot) and pltr2(3plplot) for arbitrary mappings respec‐
56 tively defined by vectors and matrices. In addition, C callback
57 routines for the transformation can be supplied by the user such
58 as the mypltr function in examples/c/x09c.c which provides a
59 general linear transformation between index coordinates and
60 world coordinates.For languages other than C you should consult
61 the PLplot documentation for the details concerning how PLTRANS‐
62 FORM_callback(3plplot) arguments are interfaced. However, in
63 general, a particular pattern of callback-associated arguments
64 such as a tr vector with 6 elements; xg and yg vectors; or xg
65 and yg matrices are respectively interfaced to a linear-trans‐
66 formation routine similar to the above mypltr function;
67 pltr1(3plplot); and pltr2(3plplot). Furthermore, some of our
68 more sophisticated bindings (see, e.g., the PLplot documenta‐
69 tion) support native language callbacks for handling index to
70 world-coordinate transformations. Examples of these various ap‐
71 proaches are given in examples/<language>x09*, examples/<lan‐
72 guage>x16*, examples/<language>x20*, examples/<language>x21*,
73 and examples/<language>x22*, for all our supported languages.
74 pltr_data (PLPointer(3plplot), input)
76 Extra parameter to help pass information to pltr0(3plplot),
77 pltr1(3plplot), pltr2(3plplot), or whatever callback routine
78 that is externally supplied.
79
82 Many developers (who are credited at http://plplot.org/credits.php)
83 have contributed to PLplot over its long history.
84
86 PLplot documentation at http://plplot.org/documentation.php.
87 July, 2023 PLCONT(3plplot)