pshistogram - Calculate and plot histograms


pshistogram [ table ] -Jx|Xparameters -Wbin_width[+l|h|b] [ -A ] [ -B[p|s]parameters ] [ -Ccpt ] [ -D[+b][+ffont][+ooff][+r] ] [ -F ] [ -Gfill ] [ -Jz|Zparameters ] [ -I[o|O] ] [ -K ] [ -Lpen ] [ -N[mode][+ppen] ] [ -O ] [ -P ] [ -Q ] [ -Rregion ] [ -S ] [ -U[stamp] ] [ -V[level] ] [ -Xx_offset ] [ -Yy_offset ] [ -Ztype ] [ -bibinary ] [ -ccopies ] [ -dinodata ] [ -fflags ] [ -hheaders ] [ -iflags ] [ -pflags ] [ -ttransp ]

Note: No space is allowed between the option flag and the associated arguments.


pshistogram reads file [or standard input] and examines the first data column (or use -i) to calculate histogram parameters based on the bin-width provided. Using these parameters, scaling, and optional range parameters it will generate PostScript code that plots a histogram. A cumulative histogram may also be specified.

Required Arguments

xscale[/yscale] (Linear scale(s) in distance unit/data unit).
Sets the bin width used for histogram calculations. The modifiers specify the handling of extreme values that fall outside the range set by -R. By default these values are ignored. Use +b to let these values be included in the first or last bins. To only include extreme values below first bin into the first bin, use +l, and to only include extreme values above the last bin into that last bin, use +h.

Optional Arguments

One or more ASCII (or binary, see -bi[ncols][type]) data table file(s) holding a number of data columns. If no tables are given then we read from standard input.
Plot the histogram horizontally from x = 0 [Default is vertically from y = 0].
-B[p|s]parameters (more ...)
Set map boundary frame and axes attributes.
Give a CPT. The mid x-value for each bar is used to look-up the bar color.
Annotate each bar with the count it represents. Append any of the following modifiers: Use +b to place the labels beneath the bars instead of above; use +f to change to another font than the default annotation font; use +o to change the offset between bar and label [6p]; use +r to rotate the labels from horizontal to vertical.
Center bin on each value. [Default is left edge].
Select filling of bars [Default is no fill].
Inquire about min/max x and y after binning. The xmin xmax ymin ymax is output; no plotting is done. Append o to output an ASCII table of the resulting x,y data instead. Upper case O will output all x,y bin data even when y == 0.
-Jz|Zparameters (more ...)
Set z-axis scaling; same syntax as -Jx.
-K (more ...)
Do not finalize the PostScript plot.
Draw bar outline using the specified pen thickness. [Default is no outline].

Draw the equivalent normal distribution; append desired pen [0.5p,black]. The mode selects which central location and scale to use:

  • 0 = mean and standard deviation [Default];
  • 1 = median and L1 scale;
  • 2 = LMS mode and scale.

The -N option may be repeated to draw several of these curves.

-O (more ...)
Append to existing PostScript plot.
-P (more ...)
Select “Portrait” plot orientation.
Draw a cumulative histogram.
-R[unit]xmin/xmax/ymin/ymax[r] (more ...)
Specify the region of interest.

For perspective view p, optionally append /zmin/zmax. (more ...) If not given, pshistogram will automatically find reasonable values for the region.

Draws a stairs-step diagram which does not include the internal bars of the default histogram.
-U[[just]/dx/dy/][c|label] (more ...)
Draw GMT time stamp logo on plot.
-V[level] (more ...)
Select verbosity level [c].


-Y[a|c|f|r][y-shift[u]] (more ...)
Shift plot origin.

Choose between 6 types of histograms:

  • 0 = counts [Default]
  • 1 = frequency_percent
  • 2 = log (1.0 + count)
  • 3 = log (1.0 + frequency_percent)
  • 4 = log10 (1.0 + count)
  • 5 = log10 (1.0 + frequency_percent).
-bi[ncols][t] (more ...)
Select native binary input. [Default is 2 input columns].
-ccopies (more ...)
Specify number of plot copies [Default is 1].
-dinodata (more ...)
Replace input columns that equal nodata with NaN.
-f[i|o]colinfo (more ...)
Specify data types of input and/or output columns.
-h[i|o][n][+c][+d][+rremark][+rtitle] (more ...)
Skip or produce header record(s).
-icols[l][sscale][ooffset][,...] (more ...)
Select input columns (0 is first column).
-p[x|y|z]azim/elev[/zlevel][+wlon0/lat0[/z0]][+vx0/y0] (more ...)
Select perspective view.
-t[transp] (more ...)
Set PDF transparency level in percent.
-^ or just -
Print a short message about the syntax of the command, then exits (NOTE: on Windows just use -).
-+ or just +
Print an extensive usage (help) message, including the explanation of any module-specific option (but not the GMT common options), then exits.
-? or no arguments
Print a complete usage (help) message, including the explanation of all options, then exits.


To draw a histogram of the data v3206.t containing seafloor depths, using a 250 meter bin width, center bars, and draw bar outline, use:

gmt pshistogram v3206.t -JXh -W250 -F -LP0.5p -V >

If you know the distribution of your data, you may explicitly specify range and scales. E.g., to plot a histogram of the y-values (2nd column) in the file errors.xy using a 1 meter bin width, plot from -10 to +10 meters @ 0.75 cm/m, annotate every 2 m and 100 counts, and use black bars, run:

gmt pshistogram errors.xy -W1 -R-10/10/0/0 -Jxc/0.01c \
                -Bx2+lError -By100+lCounts -Gblack -i1 -V >

Since no y-range was specified, pshistogram will calculate ymax in even increments of 100.


The -W option does not yet work properly with time series data (e.g., -f0T). Thus, such variable intervals as months and years are not calculated. Instead, specify your interval in the same units as the current setting of TIME_UNIT.