1 #ifndef Stats_DEFINED 2 #define Stats_DEFINED 3 4 #include "SkString.h" 5 #include "SkTSort.h" 6 7 #ifdef SK_BUILD_FOR_WIN 8 static const char* kBars[] = { ".", "o", "O" }; 9 #else 10 static const char* kBars[] = { "", "", "", "", "", "", "", "" }; 11 #endif 12 13 struct Stats { 14 Stats(const double samples[], int n) { 15 min = samples[0]; 16 max = samples[0]; 17 for (int i = 0; i < n; i++) { 18 if (samples[i] < min) { min = samples[i]; } 19 if (samples[i] > max) { max = samples[i]; } 20 } 21 22 double sum = 0.0; 23 for (int i = 0 ; i < n; i++) { 24 sum += samples[i]; 25 } 26 mean = sum / n; 27 28 double err = 0.0; 29 for (int i = 0 ; i < n; i++) { 30 err += (samples[i] - mean) * (samples[i] - mean); 31 } 32 var = err / (n-1); 33 34 SkAutoTMalloc<double> sorted(n); 35 memcpy(sorted.get(), samples, n * sizeof(double)); 36 SkTQSort(sorted.get(), sorted.get() + n - 1); 37 median = sorted[n/2]; 38 39 // Normalize samples to [min, max] in as many quanta as we have distinct bars to print. 40 for (int i = 0; i < n; i++) { 41 if (min == max) { 42 // All samples are the same value. Don't divide by zero. 43 plot.append(kBars[0]); 44 continue; 45 } 46 47 double s = samples[i]; 48 s -= min; 49 s /= (max - min); 50 s *= (SK_ARRAY_COUNT(kBars) - 1); 51 const size_t bar = (size_t)(s + 0.5); 52 SK_ALWAYSBREAK(bar < SK_ARRAY_COUNT(kBars)); 53 plot.append(kBars[bar]); 54 } 55 } 56 57 double min; 58 double max; 59 double mean; // Estimate of population mean. 60 double var; // Estimate of population variance. 61 double median; 62 SkString plot; // A single-line bar chart (_not_ histogram) of the samples. 63 }; 64 65 #endif//Stats_DEFINED 66
