mtklein | 90c471e | 2014-06-16 14:04:32 -0700 | [diff] [blame] | 1 | #ifndef Stats_DEFINED |
| 2 | #define Stats_DEFINED |
| 3 | |
mtklein | 5d9d10e | 2014-07-11 11:57:07 -0700 | [diff] [blame^] | 4 | #include <math.h> |
| 5 | |
| 6 | #include "SkString.h" |
mtklein | 40b32be | 2014-07-09 08:46:49 -0700 | [diff] [blame] | 7 | #include "SkTSort.h" |
| 8 | |
mtklein | 5d9d10e | 2014-07-11 11:57:07 -0700 | [diff] [blame^] | 9 | static const char* kBars[] = { "▁", "▂", "▃", "▄", "▅", "▆", "▇", "█" }; |
| 10 | |
mtklein | 90c471e | 2014-06-16 14:04:32 -0700 | [diff] [blame] | 11 | struct Stats { |
| 12 | Stats(const double samples[], int n) { |
| 13 | min = samples[0]; |
| 14 | max = samples[0]; |
| 15 | for (int i = 0; i < n; i++) { |
| 16 | if (samples[i] < min) { min = samples[i]; } |
| 17 | if (samples[i] > max) { max = samples[i]; } |
| 18 | } |
| 19 | |
| 20 | double sum = 0.0; |
| 21 | for (int i = 0 ; i < n; i++) { |
| 22 | sum += samples[i]; |
| 23 | } |
| 24 | mean = sum / n; |
| 25 | |
| 26 | double err = 0.0; |
| 27 | for (int i = 0 ; i < n; i++) { |
| 28 | err += (samples[i] - mean) * (samples[i] - mean); |
| 29 | } |
| 30 | var = err / (n-1); |
mtklein | 40b32be | 2014-07-09 08:46:49 -0700 | [diff] [blame] | 31 | |
| 32 | SkAutoTMalloc<double> sorted(n); |
| 33 | memcpy(sorted.get(), samples, n * sizeof(double)); |
| 34 | SkTQSort(sorted.get(), sorted.get() + n - 1); |
| 35 | median = sorted[n/2]; |
mtklein | 5d9d10e | 2014-07-11 11:57:07 -0700 | [diff] [blame^] | 36 | |
| 37 | for (int i = 0; i < n; i++) { |
| 38 | double s = samples[i]; |
| 39 | // Normalize samples to [min, max] in as many quanta as we have distinct bars to print. |
| 40 | s -= min; |
| 41 | s /= (max - min); |
| 42 | s *= (SK_ARRAY_COUNT(kBars) - 1); |
| 43 | const size_t bar = (size_t)round(s); |
| 44 | SK_ALWAYSBREAK(bar < SK_ARRAY_COUNT(kBars)); |
| 45 | plot.append(kBars[bar]); |
| 46 | } |
mtklein | 90c471e | 2014-06-16 14:04:32 -0700 | [diff] [blame] | 47 | } |
| 48 | |
| 49 | double min; |
| 50 | double max; |
mtklein | 5d9d10e | 2014-07-11 11:57:07 -0700 | [diff] [blame^] | 51 | double mean; // Estimate of population mean. |
| 52 | double var; // Estimate of population variance. |
mtklein | 40b32be | 2014-07-09 08:46:49 -0700 | [diff] [blame] | 53 | double median; |
mtklein | 5d9d10e | 2014-07-11 11:57:07 -0700 | [diff] [blame^] | 54 | SkString plot; // A single-line bar chart (_not_ histogram) of the samples. |
mtklein | 90c471e | 2014-06-16 14:04:32 -0700 | [diff] [blame] | 55 | }; |
| 56 | |
| 57 | #endif//Stats_DEFINED |