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PROGRAM:

NAME

gmtinfo - Return information about data tables

SYNOPSIS

gmtinfo [ table ] [ a|f|s ] [ ] [ [dx[/dy]] ] [ L|l|H|hcol ] [ [p|f|s]dx[/dy[/dz...] ] [
[x][y] ] [ dz[/col] ] [ [level] ] [ -bi<binary> ] [ -di<nodata> ] [ -f<flags> ] [ -g<gaps>
] [ -h<headers> ] [ -i<flags> ] [ -o<flags> ] [ -r ] [ -:[i|o] ]

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

DESCRIPTION

gmtinfo reads its standard input [or from files] and finds the extreme values in each of
the columns. It recognizes NaNs and will print warnings if the number of columns vary from
record to record. As an option, gmtinfo will find the extent of the first n columns
rounded up and down to the nearest multiple of the supplied increments. By default, this
output will be in the form -Rw/e/s/n which can be used directly in the command line for
other programs (hence only dx and dy are needed), or the output will be in column form for
as many columns as there are increments provided. A similar option (-T) will provide a
-Tzmin/zmax/dz string for makecpt.

REQUIRED ARGUMENTS

None.

OPTIONAL ARGUMENTS

table 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.

-Aa|f|s
Specify how the range should be reported. Choose -Aa for the range of all files
combined, -Af to report the range for each file separately, and -As to report the
range for each segment (in multisegment files) separately. [Default is -Aa].

-C Report the min/max values per column in separate columns [Default uses <min/max>
format]. When used, users may also use -o to limit which output columns should be
reported [all].

-D Modifies results obtained by -I by shifting the region to better align with the
center of the data. Optionally, append granularity for this shift [Default
performs an exact shift].

-EL|l|H|hcol
Returns the record whose column col contains the minimum (l) or maximum (h) value.
Upper case (L|H) works on absolute value of the data. In case of multiple matches,
only the first record is returned. If col is not specified we default to the last
column in the data.

-I[p|f|s]dx[/dy[/dz...]
Report the min/max of the first n columns to the nearest multiple of the provided
increments (separate the n increments by slashes), and output results in the form
-Rw/e/s/n (unless -C is set). If only one increment is given we also use it for the
second column (for backwards compatibility). To override this behavior, use -Ipdx.
If the input x- and y-coordinates all have the same phase shift relative to the dx
and dy increments then we use those phase shifts in determining the region, and you
may use -r to switch from gridline-registration to pixel-registration. For
irregular data both phase shifts are set to 0 and the -r is ignored. Use
-Ifdx[/dy] to report an extended region optimized to give grid dimensions for
fastest results in programs using FFTs. Use -Isdx[/dy] to report an extended
region optimized to give grid dimensions for fastest results in programs like
surface. If dx is given as - then the actual min/max of the input is given in the
-R string.

-S[x][y]
Add extra space for error bars. Useful together with -I option and when later
plotting with psxy -E. -Sx leaves space for horizontal error bars using the values
in third (2) column. -Sy leaves space for vertical error bars using the values in
third (2) column. -S or -Sxy leaves space for both error bars using the values in
third and fourth (2 and 3) columns.

-Tdz[/col]
Report the min/max of the first (0'th) column to the nearest multiple of dz and
output this in the form -Tzmin/zmax/dz. To use another column, append /col. Only
works when -I is selected.

-V[level] (more ...)
Select verbosity level [c].

-bi[ncols][t] (more ...)
Select native binary input. [Default is 2 input columns].

-dinodata (more ...)
Replace input columns that equal nodata with NaN.

-f[i|o]colinfo (more ...)
Specify data types of input and/or output columns.

-g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] (more ...)
Determine data gaps and line breaks.

-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).

-ocols[,...] (more ...)
Select output columns (0 is first column).

-r (more ...)
Set pixel node registration [gridline].

-:[i|o] (more ...)
Swap 1st and 2nd column on input and/or output.

-^ 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.

--version
Print GMT version and exit.

--show-datadir
Print full path to GMT share directory and exit.

ASCII FORMAT PRECISION

The ASCII output formats of numerical data are controlled by parameters in your gmt.conf
file. Longitude and latitude are formatted according to FORMAT_GEO_OUT, whereas other
values are formatted according to FORMAT_FLOAT_OUT. Be aware that the format in effect can
lead to loss of precision in the output, which can lead to various problems downstream. If
you find the output is not written with enough precision, consider switching to binary
output (-bo if available) or specify more decimals using the FORMAT_FLOAT_OUT setting.

EXAMPLES

To find the extreme values in the file ship_gravity.xygd:

gmt info ship_gravity.xygd

Output should look like

ship_gravity.xygd: N = 6992 <326.125/334.684> <-28.0711/-8.6837> <-47.7/177.6> <0.6/3544.9>

To find the extreme values in the file track.xy to the nearest 5 units but shifted to
within 1 unit of the data center, and use this region to draw a line using psxy, run

gmt psxy `gmt info -I5 -D1 track.xy` track.xy -Jx1 -B5 -P > track.ps

To find the min and max values for each of the first 4 columns, but rounded to integers,
and return the result individually for each data file, use

gmt info profile_*.txt -C -I1/1/1/1

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