1PLMAPLINE(3plplot) PLplot API PLMAPLINE(3plplot)
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6 plmapline - Plot all or a subset of Shapefile data using lines in world
7 coordinates
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10 plmapline(mapform, name, minx, maxx, miny, maxy, plotentries, nploten‐
11 tries)
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14 Plot all or a subset of Shapefile data using lines in world coordi‐
15 nates. Our 19th standard example demonstrates how to use this function.
16 This function plots data from a Shapefile using lines as in
17 plmap(3plplot), however it also has the option of also only drawing
18 specified elements from the Shapefile. The vector of indices of the re‐
19 quired elements are passed as a function argument. The Shapefile data
20 should include a metadata file (extension.dbf) listing all items within
21 the Shapefile. This file can be opened by most popular spreadsheet pro‐
22 grams and can be used to decide which indices to pass to this function.
23 Redacted form: plmapline(mapform, name, minx, maxx, miny, maxy, ploten‐
25 tries)
26 This function is used in example 19.
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30 mapform (PLMAPFORM_callback(3plplot), input)
31 A user supplied function to transform the coordinates given in
32 the shapefile into a plot coordinate system. By using this
33 transform, we can change from a longitude, latitude coordinate
34 to a polar stereographic project, for example. Initially,
35 x[0]..[n-1] are the longitudes and y[0]..y[n-1] are the corre‐
36 sponding latitudes. After the call to mapform(), x[] and y[]
37 should be replaced by the corresponding plot coordinates. If no
38 transform is desired, mapform can be replaced by NULL.
39 name (PLCHAR_VECTOR(3plplot), input)
41 An ascii character string specifying the file name of a set of
42 Shapefile files without the file extension.
43 minx (PLFLT(3plplot), input)
45 The minimum x value to be plotted. This must be in the same
46 units as used by the Shapefile. You could use a very large nega‐
47 tive number to plot everything, but you can improve performance
48 by limiting the area drawn. The units must match those of the
49 Shapefile projection, which may be for example longitude or dis‐
50 tance. The value of minx must be less than the value of maxx.
51 maxx (PLFLT(3plplot), input)
53 The maximum x value to be plotted. You could use a very large
54 number to plot everything, but you can improve performance by
55 limiting the area drawn.
56 miny (PLFLT(3plplot), input)
58 The minimum y value to be plotted. This must be in the same
59 units as used by the Shapefile. You could use a very large nega‐
60 tive number to plot everything, but you can improve performance
61 by limiting the area drawn. The units must match those of the
62 Shapefile projection, which may be for example latitude or dis‐
63 tance. The value of miny must be less than the value of maxy.
64 maxy (PLFLT(3plplot), input)
66 The maximum y value to be plotted. You could use a very large
67 number to plot everything, but you can improve performance by
68 limiting the area drawn.
69 plotentries (PLINT_VECTOR(3plplot), input)
71 A vector containing the zero-based indices of the Shapefile ele‐
72 ments which will be drawn. Setting plotentries to NULL will plot
73 all elements of the Shapefile.
74 nplotentries (PLINT(3plplot), input)
76 The number of items in plotentries. Ignored if plotentries is
77 NULL.
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81 Many developers (who are credited at http://plplot.org/credits.php)
82 have contributed to PLplot over its long history.
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85 PLplot documentation at http://plplot.org/documentation.php.
86 January, 2023 PLMAPLINE(3plplot)