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.TH "GMTINFO" "1gmt" "Nov 05, 2016" "5.3.1" "GMT"
.SH NAME
gmtinfo \- Return information about data tables
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.SH SYNOPSIS
.sp
\fBgmtinfo\fP [ \fItable\fP ] [  \fB\-A\fP\fBa\fP|\fBf\fP|\fBs\fP ]
[  \fB\-C\fP ]
[  \fB\-D\fP[\fIdx\fP[/\fIdy\fP]] ]
[  \fB\-E\fP\fBL\fP|\fBl\fP|\fBH\fP|\fBh\fP\fIcol\fP ]
[  \fB\-I\fP[\fBp\fP|\fBf\fP|\fBs\fP]\fIdx\fP[/\fIdy\fP[/\fIdz\fP\&...] ]
[  \fB\-L\fP ]
[  \fB\-S\fP[\fBx\fP][\fBy\fP] ]
[  \fB\-T\fP\fIdz\fP[/\fIcol\fP] ]
[  \fB\-V\fP[\fIlevel\fP] ]
[ \fB\-bi\fPbinary ]
[ \fB\-di\fPnodata ]
[ \fB\-f\fPflags ]
[ \fB\-g\fPgaps ]
[ \fB\-h\fPheaders ]
[ \fB\-i\fPflags ]
[ \fB\-o\fPflags ]
[ \fB\-r\fP ]
[ \fB\-:\fP[\fBi\fP|\fBo\fP] ]
.sp
\fBNote:\fP No space is allowed between the option flag and the associated arguments.
.SH DESCRIPTION
.sp
\fBgmtinfo\fP 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, \fBgmtinfo\fP will find the extent of the first \fIn\fP columns rounded
up and down to the nearest multiple of the supplied increments. By
default, this output will be in the form \fB\-R\fP\fIw/e/s/n\fP which can be
used directly in the command line for other programs (hence only \fIdx\fP
and \fIdy\fP are needed), or the output will be in column form for as many
columns as there are increments provided. A similar option (\fB\-T\fP) will
provide a \fB\-T\fP\fIzmin/zmax/dz\fP string for makecpt.
.SH REQUIRED ARGUMENTS
.sp
None.
.SH OPTIONAL ARGUMENTS
.INDENT 0.0
.TP
.B \fItable\fP
One or more ASCII (or binary, see \fB\-bi\fP[\fIncols\fP][\fItype\fP]) data
table file(s) holding a number of data columns. If no tables are given
then we read from standard input.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-A\fP\fBa\fP|\fBf\fP|\fBs\fP
Specify how the range should be reported. Choose \fB\-Aa\fP for the
range of all files combined, \fB\-Af\fP to report the range for each
file separately, and \fB\-As\fP to report the range for each segment
(in multisegment files) separately. [Default is \fB\-Aa\fP].
.UNINDENT
.INDENT 0.0
.TP
\fB\-C\fP
Report the min/max values per column in separate columns [Default
uses <min/max> format]. When used, users may also use \fB\-o\fP to
limit which output columns should be reported [all].
.UNINDENT
.INDENT 0.0
.TP
\fB\-D\fP
Modifies results obtained by \fB\-I\fP by shifting the region to better
align with the center of the data.  Optionally, append granularity
for this shift [Default performs an exact shift].
.UNINDENT
.INDENT 0.0
.TP
\fB\-EL\fP|\fBl\fP|\fBH\fP|\fBh\fP\fIcol\fP
Returns the record whose column \fIcol\fP contains the minimum
(\fBl\fP) or maximum (\fBh\fP) value. Upper case
(\fBL|H\fP) works on absolute value of the data. In case of multiple
matches, only the first record is returned. If \fIcol\fP is not
specified we default to the last column in the data.
.UNINDENT
.INDENT 0.0
.TP
\fB\-I\fP[\fBp\fP|\fBf\fP|\fBs\fP]\fIdx\fP[/\fIdy\fP[/\fIdz\fP\&...]
Report the min/max of the first \fIn\fP columns to the nearest multiple
of the provided increments (separate the \fIn\fP increments by slashes),
and output results in the form \fB\-R\fP\fIw/e/s/n\fP (unless \fB\-C\fP is
set). If only one increment is given we also use it for the second
column (for backwards compatibility). To override this behavior, use
\fB\-Ip\fP\fIdx\fP\&. If the input \fIx\fP\- and \fIy\fP\-coordinates all have the
same phase shift relative to the \fIdx\fP and \fIdy\fP increments then we
use those phase shifts in determining the region, and you may use
\fB\-r\fP to switch from gridline\-registration to pixel\-registration.
For irregular data both phase shifts are set to 0 and the \fB\-r\fP is ignored.
Use \fB\-If\fP\fIdx\fP[/\fIdy\fP] to report an extended region optimized
to give grid dimensions for fastest results in programs using FFTs.
Use \fB\-Is\fP\fIdx\fP[/\fIdy\fP] to report an extended region optimized to
give grid dimensions for fastest results in programs like surface.
If \fIdx\fP is given as \- then the actual min/max of the input is given in the \fB\-R\fP string.
.UNINDENT
.INDENT 0.0
.TP
\fB\-L\fP
Determines common limits across tables (\fB\-Af\fP) or segments (\fB\-As\fP).
If used with \fB\-I\fP it will round inwards so that the resulting bounds
lie within the actual data domain.
.UNINDENT
.INDENT 0.0
.TP
\fB\-S\fP[\fBx\fP][\fBy\fP]
Add extra space for error bars. Useful together with \fB\-I\fP option
and when later plotting with \fBpsxy\fP \fB\-E\fP\&. \fB\-Sx\fP leaves space
for horizontal error bars using the values in third
(2) column. \fB\-Sy\fP leaves space for vertical error
bars using the values in third (2) column. \fB\-S\fP
or \fB\-Sxy\fP leaves space for both error bars using the values in
third and fourth (2 and 3) columns.
.UNINDENT
.INDENT 0.0
.TP
\fB\-T\fP\fIdz\fP[/\fIcol\fP]
Report the min/max of the first (0\(aqth) column to the nearest
multiple of \fIdz\fP and output this in the form \fB\-T\fP\fIzmin/zmax/dz\fP\&.
To use another column, append /\fIcol\fP\&. Only works when \fB\-I\fP is selected.
.UNINDENT
.INDENT 0.0
.TP
\fB\-V\fP[\fIlevel\fP] (more ...)
Select verbosity level [c].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-bi\fP[\fIncols\fP][\fBt\fP] (more ...)
Select native binary input. [Default is 2 input columns].
.UNINDENT
.INDENT 0.0
.TP
\fB\-di\fP\fInodata\fP (more ...)
Replace input columns that equal \fInodata\fP with NaN.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-f\fP[\fBi\fP|\fBo\fP]\fIcolinfo\fP (more ...)
Specify data types of input and/or output columns.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-g\fP[\fBa\fP]\fBx\fP|\fBy\fP|\fBd\fP|\fBX\fP|\fBY\fP|\fBD\fP|[\fIcol\fP]\fBz\fP[+|\-]\fIgap\fP[\fBu\fP] (more ...)
Determine data gaps and line breaks.  
.UNINDENT
.INDENT 0.0
.TP
\fB\-h\fP[\fBi\fP|\fBo\fP][\fIn\fP][\fB+c\fP][\fB+d\fP][\fB+r\fP\fIremark\fP][\fB+r\fP\fItitle\fP] (more ...)
Skip or produce header record(s).  
.UNINDENT
.INDENT 0.0
.TP
\fB\-i\fP\fIcols\fP[\fBl\fP][\fBs\fP\fIscale\fP][\fBo\fP\fIoffset\fP][,\fI\&...\fP] (more ...)
Select input columns (0 is first column).
.UNINDENT
.INDENT 0.0
.TP
\fB\-o\fP\fIcols\fP[,...] (more ...)
Select output columns (0 is first column).
.UNINDENT
.INDENT 0.0
.TP
\fB\-r\fP (more ...)
Set pixel node registration [gridline].  
.UNINDENT
.INDENT 0.0
.TP
\fB\-:\fP[\fBi\fP|\fBo\fP] (more ...)
Swap 1st and 2nd column on input and/or output.
.UNINDENT
.INDENT 0.0
.TP
\fB\-^\fP or just \fB\-\fP
Print a short message about the syntax of the command, then exits (NOTE: on Windows use just \fB\-\fP).
.TP
\fB\-+\fP or just \fB+\fP
Print an extensive usage (help) message, including the explanation of
any module\-specific option (but not the GMT common options), then exits.
.TP
\fB\-?\fP or no arguments
Print a complete usage (help) message, including the explanation of options, then exits.
.UNINDENT
.SH ASCII FORMAT PRECISION
.sp
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 (\fB\-bo\fP if available) or
specify more decimals using the FORMAT_FLOAT_OUT setting.
.SH EXAMPLES
.sp
To find the extreme values in the file ship_gravity.xygd:
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
gmt info ship_gravity.xygd
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.sp
Output should look like
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
ship_gravity.xygd: N = 6992 <326.125/334.684> <\-28.0711/\-8.6837> <\-47.7/177.6> <0.6/3544.9>
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.sp
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
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
gmt psxy \(gagmt info \-I5 \-D1 track.xy\(ga track.xy \-Jx1 \-B5 \-P > track.ps
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.sp
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
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
gmt info profile_*.txt \-C \-I1/1/1/1
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.sp
Given seven profiles with different start and stop positions, we
want to find a range of positions, with increment of 5, that are
common to all the profiles.  We use
.INDENT 0.0
.INDENT 3.5
.INDENT 0.0
.INDENT 3.5
.sp
.nf
.ft C
gmt info profile_[123567].txt \-L \-I5
.ft P
.fi
.UNINDENT
.UNINDENT
.UNINDENT
.UNINDENT
.SH BUGS
.sp
The \fB\-I\fP option does not yet work properly with time series data
(e.g., \fB\-f\fP0T). 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\&.
.SH SEE ALSO
.sp
gmt,
gmtconvert
.SH COPYRIGHT
2016, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
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