tscale.c - ploot - simple plotting tools
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---
tscale.c (1963B)
---
1 #include "scale.h"
2
3 #include <stddef.h>
4 #include <time.h>
5
6 #include "util.h"
7
8 /*
9 * - <max ^
10 * - | Translate the coordinates between double values
11 * - <val szy and height in the plot of <row> rows.
12 * - |
13 * - <min v
14 */
15 int
16 scale_ypos(double val, double min, double max, int szy)
17 {
18 return szy * (val - min) / (max - min);
19 }
20
21 /*
22 * <---- szx ----> Translate the coordinates between the time
23 * range and position in the plot of <col> cols.
24 * t1 t t2
25 * | . . | . . |
26 */
27 int
28 scale_xpos(time_t t, time_t t1, time_t t2, int szx)
29 {
30 return szx * (t - t1) / (t2 - t1);
31 }
32
33 void
34 scale_minmax(struct csv *vl, int ncol,
35 time_t *tmin, time_t *tmax,
36 double *vmin, double *vmax)
37 {
38 double *v;
39 time_t *t;
40 size_t n;
41
42 *vmin = *vmax = 0;
43 *tmin = *tmax = *vl->t;
44
45 for (; ncol > 0; ncol--, vl++) {
46 for (t = vl->t, v = vl->v, n = vl->n; n > 0; t++, v++, n--) {
47 if (*v < *vmin) *vmin = *v;
48 if (*v > *vmax) *vmax = *v;
49 if (*t < *tmin) *tmin = *t;
50 if (*t > *tmax) *tmax = *t;
51 }
52 }
53
54 if (*tmin == *tmax)
55 err(1, "invalid time scale: min=%lld max=%lld", *tmin, *tmax);
56 }
57
58 time_t
59 scale_csvep(time_t min, time_t max, int nval)
60 {
61 time_t dt, *sc, scale[] = {
62 1, 5, 2, 10, 20, 30, 60, 60*2, 60*5, 60*10, 60*20, 60*30, 3600,
63 3600*2, 3600*5, 3600*10, 3600*18, 3600*24, 3600*24*2,
64 3600*24*5, 3600*24*10, 3600*24*20, 3600*24*30, 3600*24*50,
65 3600*24*100, 3600*24*365, 0
66 };
67
68 dt = max - min;
69
70 for (sc = scale; *sc > 0; sc++)
71 if (dt < *sc * nval)
72 return *sc;
73 return dt / nval;
74 }
75
76 double
77 scale_vstep(double min, double max, int nval)
78 {
79 double dv, d, *sc, scale[] = { 1, 2, 3, 5 };
80
81 dv = max - min;
82
83 if (dv > 1)
84 for (d = 1; d != 0; d *= 10)
85 for (sc = scale; sc < scale + LEN(scale); sc++)
86 if (dv < *sc * d * nval)
87 return *sc * d;
88 if (dv < 1)
89 for (d = 1; d != 0; d *= 10)
90 for (sc = scale + LEN(scale) - 1; sc >= scale; sc--)
91 if (dv > *sc / d * nval / 2)
92 return *sc / d;
93 return 0;
94 }