grdinfo(1) GMT grdinfo(1)
NAME
grdinfo - Extract information from grids
SYNOPSIS
grdinfo grdfiles [ -C ] [ -D[xoff[/yoff][+n] ] [ -F ] [
-I[dx[/dy]|b|i|r] ] [ -L[0|1|2|p|a] ] [ -M ] [ -Rregion ] [
-T[dz][+a[alpha]][+s] ] [ -V[level] ] [ -fflags ]
Note: No space is allowed between the option flag and the associated
arguments.
DESCRIPTION
grdinfo reads a 2-D binary grid file and reports metadata and various
statistics for the (x,y,z) data in the grid file(s). The output infor-
mation contains the minimum/maximum values for x, y, and z, where the
min/max of z occur, the x- and y-increments, and the number of x and y
nodes, and [optionally] the mean, standard deviation, and/or the
median, median absolute deviation of z, and/or the mode (LMS), LMS
scale of z, and number of nodes set to NaN. We also report if the grid
is pixel- or gridline-registered and if it is a Cartesian or Geographic
data set (based on metadata in the file).
REQUIRED ARGUMENTS
grdfile
The name of one or several 2-D grid files. (See GRID FILE FOR-
MATS below.)
OPTIONAL ARGUMENTS
-C Formats the report using tab-separated fields on a single line.
The output is w e s n z0 z1 dx dy nx ny[ x0 y0 x1 y1 ] [ med
scale ] [mean std rms] [n_nan]. The data in brackets are output
only if the corresponding options -M, -L1, -L2, and -M are used,
respectively. If the -I option is used, the output format is
instead NF w e s n z0 z1, where NF is the total number of grids
read and w e s n are rounded off (see -I).
-D[xoff[/yoff][+i]
Divide a single gridas domain (or the -R domain, if no grid
given) into tiles of size dx times dy (set via -I). You can
specify overlap between tiles by appending xoff[/yoff]. If the
single grid is given you may use the modifier +i to ignore tiles
that have no data within each tile subregion.
-F Report grid domain and x/y-increments in world mapping format
[Default is generic]. Does not apply to the -C option.
-I[dx[/dy]|b|i|r]
Report the min/max of the region to the nearest multiple of dx
and dy, and output this in the form -Rw/e/s/n (unless -C is
set). To report the actual grid region, select -Ir. For a grid
produced by the img supplement (a Cartesian Mercator grid), the
exact geographic region is given with -Ii (if not found then we
return the actual grid region instead). If no argument is given
then we report the grid increment in the form -Ixinc/yinc. If
-Ib is given we write each gridas bounding box polygon instead.
-L[0|1|2|p|a]
-L0 Report range of z after actually scanning the data, not
just reporting what the header says.
-L1 Report median and L1 scale of z (L1 scale = 1.4826 *
Median Absolute Deviation (MAD)).
-L2 Report mean, standard deviation, and root-mean-square
(rms) of z.
-Lp Report mode (LMS) and LMS scale of z.
-La All of the above.
Note: If the grid is geographic then each node represents a
physical area that decreases with increasing latitude. We
therefore report spherically weighted statistical estimates for
such grids.
-M Find and report the location of min/max z-values, and count and
report the number of nodes set to NaN, if any.
-Rxmin/xmax/ymin/ymax[+r][+uunit] (more a|)
Specify the region of interest. Using the -R option will select
a subsection of the input grid(s). If this subsection exceeds
the boundaries of the grid, only the common region will be
extracted.
-T[dz][+a[alpha]][+s]
Determine min and max z-value. If dz is provided then we first
round these values off to multiples of dz. To exclude the two
tails of the distribution when determining the min and max you
can add +a to set the alpha value (in percent [2]): We then sort
the grid, exclude the data in the 0.5*alpha and 100 - 0.5*alpha
tails, and revise the min and max. To force a symmetrical range
about zero, using minus/plus the max absolute value of the two
extremes, append +s. We report the result via the text string
-Tzmin/zmax or -Tzmin/zmax/dz (if dz was given) as expected by
makecpt.
-V[level] (more a|)
Select verbosity level [c].
-f[i|o]colinfo (more a|)
Specify data types of input and/or output columns.
-^ 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 explana-
tion 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.
GRID FILE FORMATS
By default GMT writes out grid as single precision floats in a
COARDS-complaint netCDF file format. However, GMT is able to produce
grid files in many other commonly used grid file formats and also
facilitates so called apackinga of grids, writing out floating point
data as 1- or 2-byte integers. (more a|)
EXAMPLES
To obtain all the information about the data set in file
hawaii_topo.nc:
gmt grdinfo -L1 -L2 -M hawaii_topo.nc
SEE ALSO
gmt(1), grd2cpt(1), grd2xyz(1), grdedit(1)
COPYRIGHT
2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
5.4.2 Jun 24, 2017 grdinfo(1)
gmt5 5.4.2 - Generated Wed Jun 28 20:20:12 CDT 2017