tally: simplify, add Y axis to graph.
authorRusty Russell <rusty@rustcorp.com.au>
Sat, 25 Sep 2010 02:11:38 +0000 (11:41 +0930)
committerRusty Russell <rusty@rustcorp.com.au>
Sat, 25 Sep 2010 02:11:38 +0000 (11:41 +0930)
ccan/tally/tally.c
ccan/tally/tally.h
ccan/tally/test/run-histogram.c

index 88407cf985ccfb30996383b51e7c291af00319fe..9f2a4591f8c3ce5ddd05b8f29702ff2761784dad 100644 (file)
@@ -15,12 +15,11 @@ struct tally {
        ssize_t min, max;
        size_t total[2];
        /* This allows limited frequency analysis. */
-       size_t buckets;
-       size_t step_bits;
+       unsigned buckets, step_bits;
        size_t counts[1 /* [buckets] */ ];
 };
 
-struct tally *tally_new(size_t buckets)
+struct tally *tally_new(unsigned buckets)
 {
        struct tally *tally;
 
@@ -29,20 +28,8 @@ struct tally *tally_new(size_t buckets)
                return NULL;
        tally = malloc(sizeof(*tally) + sizeof(tally->counts[0])*buckets);
        if (tally) {
-               /* SSIZE_MAX isn't portable, so make it one of these types. */
-               BUILD_ASSERT(sizeof(tally->min) == sizeof(int)
-                            || sizeof(tally->min) == sizeof(long)
-                            || sizeof(tally->min) == sizeof(long long));
-               if (sizeof(tally->min) == sizeof(int)) {
-                       tally->min = INT_MAX;
-                       tally->max = INT_MIN;
-               } else if (sizeof(tally->min) == sizeof(long)) {
-                       tally->min = LONG_MAX;
-                       tally->max = LONG_MIN;
-               } else if (sizeof(tally->min) == sizeof(long long)) {
-                       tally->min = (ssize_t)LLONG_MAX;
-                       tally->max = (ssize_t)LLONG_MIN;
-               }
+               tally->max = ((size_t)1 << (SIZET_BITS - 1));
+               tally->min = ~tally->max;
                tally->total[0] = tally->total[1] = 0;
                /* There is always 1 bucket. */
                tally->buckets = buckets+1;
@@ -444,7 +431,7 @@ char *tally_histogram(const struct tally *tally,
                memcpy(tmp->counts, tally->counts,
                       sizeof(tally->counts[0]) * tmp->buckets);
                while ((max_bucket = get_max_bucket(tmp)) >= height)
-                       renormalize(tmp, tmp->min, tmp->max *= 2);
+                       renormalize(tmp, tmp->min, tmp->max * 2);
                /* Restore max */
                tmp->max = tally->max;
                tally = tmp;
@@ -463,23 +450,29 @@ char *tally_histogram(const struct tally *tally,
                free(tmp);
                return NULL;
        }
+
        for (i = 0; i < height; i++) {
-               unsigned covered = 0;
-               count = (double)tally->counts[i] / largest_bucket * width;
+               unsigned covered = 1;
+               count = (double)tally->counts[i] / largest_bucket * (width-1)+1;
 
                if (i == 0)
                        covered = snprintf(p, width, "%zi", tally->min);
                else if (i == height - 1)
                        covered = snprintf(p, width, "%zi", tally->max);
-               if (covered) {
-                       if (covered > width)
-                               covered = width;
-                       p += covered;
-                       if (count > covered)
-                               count -= covered;
-                       else
-                               count = 0;
-               }
+               else if (i == bucket_of(tally->min, tally->step_bits, 0))
+                       *p = '+';
+               else
+                       *p = '|';
+
+               if (covered > width)
+                       covered = width;
+               p += covered;
+
+               if (count > covered)
+                       count -= covered;
+               else
+                       count = 0;
+
                memset(p, '*', count);
                p += count;
                *p = '\n';
index b38cd70646f3b6205eb71e4ef07a01c2afec20cd..e7157175075cb556d2ff7cd5c74d07b95ee3fd3d 100644 (file)
@@ -10,9 +10,11 @@ struct tally;
  *
  * This allocates a tally structure using malloc().  The greater the value
  * of @buckets, the more accurate tally_approx_median() and tally_approx_mode()
- * and tally_graph() will be, but more memory is consumed.
+ * and tally_histogram() will be, but more memory is consumed.  If you want
+ * to use tally_histogram(), the optimal bucket value is the same as that
+ * @height argument.
  */
-struct tally *tally_new(size_t buckets);
+struct tally *tally_new(unsigned int buckets);
 
 /**
  * tally_add - add a value.
index 8f8bd2ff3aaa8b521213727fe7b197489a2e3c1a..2690cebdff9aec5e555298baf92e17f65fcd6a21 100644 (file)
@@ -8,7 +8,7 @@ int main(void)
        char *graph, *p;
        bool trunc;
 
-       plan_tests(100 + 1 + 10 + 1 + 100 + 1 + 10 + 1 + 10 + 2 + 1);
+       plan_tests(100 + 1 + 10 + 1 + 100 + 1 + 10 + 1 + 10 * 2 + 1);
 
        /* Uniform distribution, easy. */
        tally = tally_new(100);
@@ -100,11 +100,16 @@ int main(void)
                /* Check min/max labels. */
                if (i == 0)
                        ok1(strncmp(p, "-5*", 3) == 0);
-               if (i == 9)
+               else if (i == 9)
                        ok1(strncmp(p, "4*", 2) == 0);
+               else if (i == 5)
+                       ok1(p[0] == '+'); /* 0 marker */
+               else
+                       ok1(p[0] == '|');
                p = eol + 1;
        }
        ok1(!*p);
+       diag("Here's the pretty: %s", graph);
        free(graph);
        free(tally);