diff options
| -rw-r--r-- | histogram.cpp | 134 |
1 files changed, 87 insertions, 47 deletions
diff --git a/histogram.cpp b/histogram.cpp index 855776d..c7bbc6a 100644 --- a/histogram.cpp +++ b/histogram.cpp @@ -10,12 +10,15 @@ static const char *argv0; void usage() { - std::cerr << "Usage: " << argv0 << " [<lowbound> <highbound>] [<nbins>]" << std::endl + std::cerr << "Usage: " << argv0 << " [-h] [<lowbound> <highbound>] [<nbins>]" << std::endl << "Prints a simple histogram of stdin data in your terminal, using" << std::endl << "either the given lower and upper bounds, or the minimum and" << std::endl << "maximum extracted from the data." << std::endl - << "The number of bins can also be passed." << std::endl - << "Data on stdin is assumed to be a list of floating-point values." << std::endl; + << "The number of bins can also be passed. (If unspecified, defaults" << std::endl + << "to 10.)" << std::endl + << "Data on stdin is assumed to be a list of floating-point values." << std::endl + << std::endl + << " -h Show this help." << std::endl; } double parsefloat(const char *s, const char *errprefix) { @@ -45,27 +48,46 @@ int main(int argc, char **argv) { const int64_t BARWIDTH = 80; - double low, high; + double low = 0, high = 1; // will be overwritten either from arguments or from data bool havebounds; int64_t nbins = 10; - if (argc == 1) { - havebounds = false; - } else if (argc == 2) { - havebounds = false; - nbins = parseint(argv[1], "Invalid number"); - } else if (argc == 3) { - havebounds = true; - low = parsefloat(argv[1], "Invalid number"); - high = parsefloat(argv[2], "Invalid number"); - } else if (argc == 4) { - havebounds = true; - low = parsefloat(argv[1], "Invalid number"); - high = parsefloat(argv[2], "Invalid number"); - nbins = parseint(argv[3], "Invalid number"); - } else { - usage(); - return 1; + std::vector<char*> plainargs; + for (int i = 1; i < argc; i++) { + if (strcmp(argv[i], "-h") == 0) { + usage(); + return 0; + } else { + plainargs.push_back(argv[i]); + } + } + + switch (plainargs.size()) { + case 0: + havebounds = false; + break; + + case 1: + havebounds = false; + nbins = parseint(plainargs[0], "Invalid number"); + break; + + case 2: + havebounds = true; + low = parsefloat(plainargs[0], "Invalid number"); + high = parsefloat(plainargs[1], "Invalid number"); + break; + + case 3: + havebounds = true; + low = parsefloat(plainargs[0], "Invalid number"); + high = parsefloat(plainargs[1], "Invalid number"); + nbins = parseint(plainargs[2], "Invalid number"); + break; + + default: + usage(); + return 1; } if (nbins < 1) { @@ -80,26 +102,47 @@ int main(int argc, char **argv) { return 1; } - double minval = INFINITY, maxval = -INFINITY; + // Read data and collect low and high bounds, if necessary std::vector<double> values; - while (true) { - double v; - std::cin >> v; - if (!std::cin) break; - values.push_back(v); - if (v < minval) minval = v; - if (v > maxval) maxval = v; - } - if (!havebounds) { - low = minval; - high = maxval; + { + double minval = INFINITY, maxval = -INFINITY; + while (true) { + double v; + std::cin >> v; + if (!std::cin) { + // Check whether it was invalid data or EOF that let the read fail + std::cin.clear(); + std::string str; + std::cin >> str; + if (std::cin) { + std::cerr << "histogram: Invalid data starting with word '" + << str << "'" << std::endl; + usage(); + return 1; + } else { + // EOF, so we're done + break; + } + } + values.push_back(v); + if (v < minval) minval = v; + if (v > maxval) maxval = v; + } + if (!havebounds) { + low = minval; + high = maxval; + } } - std::sort(values.begin(), values.end()); + if (low == high) { + std::cerr << "histogram: Plot range contains only one point: " << low << std::endl; + usage(); + return 1; + } - std::vector<int64_t> histogram(nbins); + // Collect data in the histogram + std::vector<int64_t> histogram(nbins, 0); - int64_t binidx = 0, tally = 0, maxtally = -1; for (double v : values) { if (v < low || v > high) { // cerr << "Point " << v << " out of range!" << endl; @@ -108,22 +151,18 @@ int main(int argc, char **argv) { int64_t bin = (v - low) / (high - low) * nbins; if (bin == nbins) bin--; assert(bin >= 0 && bin < nbins); - if (bin != binidx) { - histogram[binidx] = tally; - if (tally > maxtally) maxtally = tally; - binidx = bin; - tally = 0; - } - tally++; + histogram[bin]++; } - histogram[binidx] = tally; - if (tally > maxtally) maxtally = tally; + + // Compute statistics + int64_t maxtally = *std::max_element(histogram.begin(), histogram.end()); if (maxtally == 0) { std::cerr << "histogram: No data in range" << std::endl; return 1; } + // Print histogram char fullbar[BARWIDTH + 1]; memset(fullbar, '#', BARWIDTH); fullbar[BARWIDTH] = '\0'; @@ -133,11 +172,12 @@ int main(int argc, char **argv) { for (size_t i = 0; i < histogram.size(); i++) { int64_t tally = histogram[i]; + double binlow = low + (double)i / nbins * (high - low); + double binhigh = low + (double)(i + 1) / nbins * (high - low); int64_t width = BARWIDTH * tally / maxtally; char terminator = ")]"[i == histogram.size() - 1]; std::cout << fullbar + BARWIDTH - width << emptybar + width - << " [" << std::setw(11) << low + (double)i / nbins * (high - low) << " - " - << std::setw(11) << low + (double)(i + 1) / nbins * (high - low) << terminator + << " [" << std::setw(11) << binlow << " - " << std::setw(11) << binhigh << terminator << " [" << tally << "]" << std::endl; } } |