makeHistogram.c File Reference

Compiles histograms from data points. More...

#include "mdb.h"

Go to the source code of this file.

Functions
long	make_histogram (double *hist, long n_bins, double lo, double hi, double *data, int64_t n_pts, long new_start)
	Compiles a histogram from data points.
long	make_histogram_weighted (double *hist, long n_bins, double lo, double hi, double *data, long n_pts, long new_start, double *weight)
	Compiles a weighted histogram from data points.
long	computeMode (double *result, double *data, long pts, double binSize, long bins)
	Computes the mode of a dataset using histogram binning.

Detailed Description

Compiles histograms from data points.

This file contains functions to compile histograms from data points. It provides both standard and weighted histogram functions, as well as a function to compute the mode of a dataset.

Copyright

• (c) 2002 The University of Chicago, as Operator of Argonne National Laboratory.
• (c) 2002 The Regents of the University of California, as Operator of Los Alamos National Laboratory.

License

This file is distributed under the terms of the Software License Agreement found in the file LICENSE included with this distribution.

Author

M. Borland, C. Saunders, R. Soliday

Definition in file makeHistogram.c.

Function Documentation

computeMode()

long computeMode	(	double *	result,
		double *	data,
		long	pts,
		double	binSize,
		long	bins )

Computes the mode of a dataset using histogram binning.

Parameters

result	Pointer to store the computed mode value.
data	Pointer to the data array.
pts	Number of data points.
binSize	Size of each histogram bin. If greater than 0, determines the bin size; otherwise, the number of bins is used.
bins	Number of bins in the histogram.

Returns

1 on success,

-1 if invalid binSize and bins parameters,

-2 if pts <= 0,

-3 if data is NULL,

-4 if result is NULL.

Definition at line 115 of file makeHistogram.c.

                                                                                    {
  double min, max;
  int64_t imin, imax;
  double *histogram;
 
  if ((binSize <= 0 && bins <= 2) || (binSize > 0 && bins > 2))
    return -1;
  if (pts <= 0)
    return -2;
  if (!data)
    return -3;
  if (!result)
    return -4;
  if (pts == 1) {
    *result = data[0];
    return 1;
  }
  find_min_max(&min, &max, data, pts);
  /* add buffer bins and compute bin size or number of bins */
  if (binSize > 0) {
    max += binSize;
    min -= binSize;
    bins = (max - min) / binSize + 0.5;
  } else {
    binSize = (max - min) / bins;
    max += binSize;
    min -= binSize;
    bins += 2;
    binSize = (max - min) / bins;
  }
  if (!(histogram = malloc(sizeof(*histogram) * bins)))
    bomb("memory allocation failure (computeMode)", NULL);
  make_histogram(histogram, bins, min, max, data, pts, 1);
  index_min_max(&imin, &imax, histogram, bins);
  free(histogram);
  *result = (imax + 0.5) * binSize + min;
  return 1;
}

make_histogram()

long make_histogram	(	double *	hist,
		long	n_bins,
		double	lo,
		double	hi,
		double *	data,
		int64_t	n_pts,
		long	new_start )

Compiles a histogram from data points.

Parameters

hist	Pointer to the histogram array to be filled.
n_bins	Number of bins in the histogram.
lo	Lower bound of the histogram range.
hi	Upper bound of the histogram range.
data	Pointer to the data array.
n_pts	Number of data points.
new_start	Flag indicating whether to initialize the histogram (1 to initialize, 0 to accumulate).

Returns

Returns the total number of points binned.

Definition at line 33 of file makeHistogram.c.

                                 {
  static long bin;
  static int64_t i;
  static double bin_size, dbin;
 
  if (new_start) {
    bin_size = (hi - lo) / n_bins;
    for (i = 0; i < n_bins; i++)
      hist[i] = 0;
  }
 
  for (i = 0; i < n_pts; i++) {
    bin = (dbin = (data[i] - lo) / bin_size);
    if (dbin < 0)
      continue;
    if (bin < 0 || bin >= n_bins)
      continue;
    hist[bin] += 1;
  }
 
  for (i = bin = 0; i < n_bins; i++)
    bin += hist[i];
 
  return (bin);
}

make_histogram_weighted()

long make_histogram_weighted	(	double *	hist,
		long	n_bins,
		double	lo,
		double	hi,
		double *	data,
		long	n_pts,
		long	new_start,
		double *	weight )

Compiles a weighted histogram from data points.

Parameters

hist	Pointer to the histogram array to be filled.
n_bins	Number of bins in the histogram.
lo	Lower bound of the histogram range.
hi	Upper bound of the histogram range.
data	Pointer to the data array.
n_pts	Number of data points.
new_start	Flag indicating whether to initialize the histogram (1 to initialize, 0 to accumulate).
weight	Pointer to the weights array corresponding to each data point.

Returns

Returns the total number of points binned.

Definition at line 74 of file makeHistogram.c.

                                              {
  static long bin, i, count;
  static double bin_size, dbin;
 
  if (new_start) {
    count = 0;
    bin_size = (hi - lo) / n_bins;
    for (i = 0; i < n_bins; i++)
      hist[i] = 0;
  }
 
  for (i = 0; i < n_pts; i++) {
    bin = (dbin = (data[i] - lo) / bin_size);
    if (dbin < 0)
      continue;
    if (bin < 0 || bin >= n_bins)
      continue;
    hist[bin] += weight[i];
    count++;
  }
 
  return (count);
}