NAME¶
grdinfo - Extract information from grids
SYNOPSIS¶
grdinfo grdfiles [
-C ] [
-F ] [
-I[
dx[/
dy]|
r|
b] ] [
-L[
0|
1|
2] ] [
-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 information 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, L1 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 FORMATS
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).
- -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]|r|b]
- 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. If
no argument is given then we report the grid increment in the form
-I xinc/yinc. If -Ib is given we write each grid's
bounding box polygon instead.
- -L[0|1|2]
- -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.
- -M
- Find and report the location of min/max z-values, and count and report the
number of nodes set to NaN, if any.
- -R[unit]xmin/xmax/ymin/ymax[r]
(more ...)
- 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 ...)
- Select verbosity level [c].
- -f[i|o]colinfo (more ...)
- 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 use just -).
- -+ 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
options, then exits.
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
"packing" of grids, writing out floating point data as 1- or 2-byte
integers.
(more ...)
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,
grd2cpt,
grd2xyz,
grdedit
COPYRIGHT¶
2016, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
