grdinfo
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
-Ixinc/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.
Examples
To obtain all the information about the data set in file hawaii_topo.nc:
gmt grdinfo -L1 -L2 -M hawaii_topo.nc