1 /* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef Stats_DEFINED 9 #define Stats_DEFINED 10 11 #include "SkFloatingPoint.h" 12 #include "SkString.h" 13 #include "SkTSort.h" 14 15 #ifdef SK_BUILD_FOR_WIN 16 static const char* kBars[] = { ".", "o", "O" }; 17 #else 18 static const char* kBars[] = { "▁", "▂", "▃", "▄", "▅", "▆", "▇", "█" }; 19 #endif 20 21 struct Stats { StatsStats22 Stats(const SkTArray<double>& samples, bool want_plot) { 23 int n = samples.count(); 24 if (!n) { 25 min = max = mean = var = median = 0; 26 return; 27 } 28 29 min = samples[0]; 30 max = samples[0]; 31 for (int i = 0; i < n; i++) { 32 if (samples[i] < min) { min = samples[i]; } 33 if (samples[i] > max) { max = samples[i]; } 34 } 35 36 double sum = 0.0; 37 for (int i = 0 ; i < n; i++) { 38 sum += samples[i]; 39 } 40 mean = sum / n; 41 42 double err = 0.0; 43 for (int i = 0 ; i < n; i++) { 44 err += (samples[i] - mean) * (samples[i] - mean); 45 } 46 var = sk_ieee_double_divide(err, n-1); 47 48 SkAutoTMalloc<double> sorted(n); 49 memcpy(sorted.get(), samples.begin(), n * sizeof(double)); 50 SkTQSort(sorted.get(), sorted.get() + n - 1); 51 median = sorted[n/2]; 52 53 // Normalize samples to [min, max] in as many quanta as we have distinct bars to print. 54 for (int i = 0; want_plot && i < n; i++) { 55 if (min == max) { 56 // All samples are the same value. Don't divide by zero. 57 plot.append(kBars[0]); 58 continue; 59 } 60 61 double s = samples[i]; 62 s -= min; 63 s /= (max - min); 64 s *= (SK_ARRAY_COUNT(kBars) - 1); 65 const size_t bar = (size_t)(s + 0.5); 66 SkASSERT_RELEASE(bar < SK_ARRAY_COUNT(kBars)); 67 plot.append(kBars[bar]); 68 } 69 } 70 71 double min; 72 double max; 73 double mean; // Estimate of population mean. 74 double var; // Estimate of population variance. 75 double median; 76 SkString plot; // A single-line bar chart (_not_ histogram) of the samples. 77 }; 78 79 #endif//Stats_DEFINED 80