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<title>GMTSELECT</title>
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<h1 align="center">GMTSELECT</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#OPTIONS">OPTIONS</a><br>
<a href="#ASCII FORMAT PRECISION">ASCII FORMAT PRECISION</a><br>
<a href="#NOTE ON PROCESSING ASCII INPUT RECORDS">NOTE ON PROCESSING ASCII INPUT RECORDS</a><br>
<a href="#NOTE ON DISTANCES">NOTE ON DISTANCES</a><br>
<a href="#EXAMPLES">EXAMPLES</a><br>
<a href="#GSHHS INFORMATION">GSHHS INFORMATION</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">gmtselect
− Select data subsets based on multiple spatial
criteria</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
[ <i>infiles</i> ] [
<b>−A</b><i>min_area</i>[<i>/min_level/max_level</i>][<b>+r</b>|<b>l</b>][<b>p</b><i>percent</i>]
] [ <b>−C</b>[<b>f</b>]<i>dist/ptfile</i> ] [
<b>−D</b><i>resolution</i>[<b>+</b>] ] [
<b>−F</b><i>polygonfile</i> ] [
<b>−H</b>[<b>i</b>][<i>nrec</i>] ] [
<b>−I</b>[<b>cflrsz</b>] ] [
<b>−J</b><i>parameters</i> ] [
<b>−L</b>[<b>p</b>]<i>dist/linefile</i> ] [
<b>−N</b><i>maskvalues</i>[<b>o</b>] ] [
<b>−R</b><i>west</i>/<i>east</i>/<i>south</i>/<i>north</i>[<b>r</b>]
] [ <b>−V</b> ] [ <b>−Z</b><i>min/max</i>] ] [
<b>−:</b>[<b>i</b>|<b>o</b>] ] [
<b>−b</b>[<b>i</b>|<b>o</b>][<b>s</b>|<b>S</b>|<b>d</b>|<b>D</b>[<i>ncol</i>]|<b>c</b>[<i>var1</i><b>/</b><i>...</i>]]
] [ <b>−f</b>[<b>i</b>|<b>o</b>]<i>colinfo</i> ] [
<b>−m</b>[<b>i</b>|<b>o</b>][<i>flag</i>] ]</p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
is a filter that reads (longitude, latitude) positions from
the first 2 columns of <i>infiles</i> [or standard input]
and uses a combination of 1-6 criteria to pass or reject the
records. Records can be selected based on whether or not
they are 1) inside a rectangular region (<b>−R</b>
[and <b>−J</b>]), 2) within <i>dist</i> km of any
point in <i>ptfile</i>, 3) within <i>dist</i> km of any line
in <i>linefile</i>, 4) inside one of the polygons in the
<i>polygonfile</i>, 5) inside geographical features (based
on coastlines), or 6) has z-values within a given range. The
sense of the tests can be reversed for each of these 6
criteria by using the <b>−I</b> option. See option
<b>−:</b> on how to read (latitude,longitude) files.
<i><br>
infiles</i></p>
<p style="margin-left:22%;">ASCII (or binary, see
<b>−b</b>) data file(s) to be operated on. If not
given, standard input is read.</p>
<h2>OPTIONS
<a name="OPTIONS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">No space
between the option flag and the associated arguments.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−A</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Features with an area smaller than <i>min_area</i> in
km^2 or of hierarchical level that is lower than
<i>min_level</i> or higher than <i>max_level</i> will not be
plotted [Default is 0/0/4 (all features)]. Level 2 (lakes)
contains regular lakes and wide river bodies which we
normally include as lakes; append <b>+r</b> to just get
river-lakes or <b>+l</b> to just get regular lakes (requires
GSHHS 2.0.1 or higher). Finally, append
<b>+p</b><i>percent</i> to exclude polygons whose percentage
area of the corresponding full-resolution feature is less
than <i>percent</i> (requires GSHHS 2.0 or higher). See
GSHHS INFORMATION below for more details. Ignored unless
<b>−N</b> is set.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−C</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Pass all records whose location is within <i>dist</i> of
any of the points in the ASCII file <i>ptfile</i>. If
<i>dist</i> is zero then the 3rd column of <i>ptfile</i>
must have each point’s individual radius of influence.
Distances are Cartesian and in user units; specify
<b>−fg</b> to indicate spherical distances in km. Use
<b>−Cf</b> to indicate you want flat Earth distances
(quicker but approximate) rather than geodesic distances
(slower but exact). If <b><A HREF="gmtdefaults.html#ELLIPSOID">ELLIPSOID</A></b> is spherical then
geodesics become great circles (faster to compute than
geodesic). Alternatively, if <b>−R</b> and
<b>−J</b> are used then geographic coordinates are
projected to map coordinates (in cm, inch, m, or points, as
determined by <b><A HREF="gmtdefaults.html#MEASURE_UNIT">MEASURE_UNIT</A></b>) before Cartesian
distances are compared to <i>dist</i>.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−D</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Ignored unless <b>−N</b> is set. Selects the
resolution of the coastline data set to use ((<b>f</b>)ull,
(<b>h</b>)igh, (<b>i</b>)ntermediate, (<b>l</b>)ow, or
(<b>c</b>)rude). The resolution drops off by ~80% between
data sets. [Default is <b>l</b>]. Append <b>+</b> to
automatically select a lower resolution should the one
requested not be available [abort if not found]. Note that
because the coastlines differ in details it is not
guaranteed that a point will remain inside [or outside] when
a different resolution is selected.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−F</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Pass all records whose location is within one of the
closed polygons in the multiple-segment file
<i>polygonfile</i>. For spherical polygons (lon, lat), make
sure no consecutive points are separated by 180 degrees or
more in longitude. Note that <i>polygonfile</i> must be in
ASCII regardless of whether <b>−b</b> is used.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−H</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Input file(s) has header record(s). If used, the default
number of header records is <b><A HREF="gmtdefaults.html#N_HEADER_RECS">N_HEADER_RECS</A></b>. Use
<b>−Hi</b> if only input data should have header
records [Default will write out header records if the input
data have them]. Blank lines and lines starting with # are
always skipped.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−I</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Reverses the sense of the test for each of the criteria
specified:</p> </td></tr>
</table>
<p style="margin-left:22%;"><b>c</b> select records NOT
inside any point’s circle of influence. <b><br>
f</b> select records NOT inside any of the polygons. <b><br>
l</b> select records NOT within the specified distance of
any line. <b><br>
r</b> select records NOT inside the specified rectangular
region. <b><br>
s</b> select records NOT considered inside as specified by
<b>−N</b> (and <b>−A</b>, <b>−D</b>).
<b><br>
z</b> select records NOT within the range specified by
<b>−Z</b>.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em"><b>−J</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Selects the map projection.
Scale is UNIT/degree, 1:xxxxx, or width in UNIT (upper case
modifier). UNIT is cm, inch, or m, depending on the
<b><A HREF="gmtdefaults.html#MEASURE_UNIT">MEASURE_UNIT</A></b> setting in .gmtdefaults4, but this can
be overridden on the command line by appending <b>c</b>,
<b>i</b>, or <b>m</b> to the scale/width value. When central
meridian is optional, default is center of longitude range
on <b>−R</b> option. Default standard parallel is the
equator. For map height, max dimension, or min dimension,
append <b>h</b>, <b>+</b>, or <b>-</b> to the width,
respectively.</p> </td></tr>
</table>
<p style="margin-left:22%;">More details can be found in
the <b><A HREF="psbasemap.html">psbasemap</A></b> man pages.</p>
<p style="margin-left:22%; margin-top: 1em"><b>CYLINDRICAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jc</b><i>lon0/lat0/scale</i>
(Cassini) <b><br>
−Jcyl_stere</b>/[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Stereographic) <b><br>
−Jj</b>[<i>lon0/</i>]<i>scale</i> (Miller) <b><br>
−Jm</b>[<i>lon0</i>/[<i>lat0/</i>]]<i>scale</i>
(Mercator) <b><br>
−Jm</b><i>lon0/lat0/scale</i> (Mercator - Give
meridian and standard parallel) <b><br>
−Jo</b>[<b>a</b>]<i>lon0/lat0/azimuth/scale</i>
(Oblique Mercator - point and azimuth) <b><br>
−Jo</b>[<b>b</b>]<i>lon0/lat0/lon1/lat1/scale</i>
(Oblique Mercator - two points) <b><br>
−Joc</b><i>lon0/lat0/lonp/latp/scale</i> (Oblique
Mercator - point and pole) <b><br>
−Jq</b>[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Equidistant) <b><br>
−Jt</b><i>lon0/</i>[<i>lat0/</i>]<i>scale</i> (TM -
Transverse Mercator) <b><br>
−Ju</b><i>zone/scale</i> (UTM - Universal Transverse
Mercator) <b><br>
−Jy</b>[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
(Cylindrical Equal-Area)</p>
<p style="margin-left:22%; margin-top: 1em"><b>CONIC
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jb</b><i>lon0/lat0/lat1/lat2/scale</i>
(Albers) <b><br>
−Jd</b><i>lon0/lat0/lat1/lat2/scale</i> (Conic
Equidistant) <b><br>
−Jl</b><i>lon0/lat0/lat1/lat2/scale</i> (Lambert Conic
Conformal) <b><br>
−Jpoly</b>/[<i>lon0/</i>[<i>lat0/</i>]]<i>scale</i>
((American) Polyconic)</p>
<p style="margin-left:22%; margin-top: 1em"><b>AZIMUTHAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Ja</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Lambert Azimuthal Equal-Area) <b><br>
−Je</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Azimuthal Equidistant) <b><br>
−Jf</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Gnomonic) <b><br>
−Jg</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(Orthographic) <b><br>
−Jg</b><i>lon0/lat0/altitude/azimuth/tilt/twist/Width/Height/scale</i>
(General Perspective). <b><br>
−Js</b><i>lon0/lat0</i>[<i>/horizon</i>]<i>/scale</i>
(General Stereographic)</p>
<p style="margin-left:22%; margin-top: 1em"><b>MISCELLANEOUS
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jh</b>[<i>lon0/</i>]<i>scale</i>
(Hammer) <b><br>
−Ji</b>[<i>lon0/</i>]<i>scale</i> (Sinusoidal) <b><br>
−Jkf</b>[<i>lon0/</i>]<i>scale</i> (Eckert IV) <b><br>
−Jk</b>[<b>s</b>][<i>lon0/</i>]<i>scale</i> (Eckert
VI) <b><br>
−Jn</b>[<i>lon0/</i>]<i>scale</i> (Robinson) <b><br>
−Jr</b>[<i>lon0/</i>]<i>scale</i> (Winkel Tripel)
<b><br>
−Jv</b>[<i>lon0/</i>]<i>scale</i> (Van der Grinten)
<b><br>
−Jw</b>[<i>lon0/</i>]<i>scale</i> (Mollweide)</p>
<p style="margin-left:22%; margin-top: 1em"><b>NON-GEOGRAPHICAL
PROJECTIONS:</b></p>
<p style="margin-left:22%; margin-top: 1em"><b>−Jp</b>[<b>a</b>]<i>scale</i>[<i>/origin</i>][<b>r</b>|<b>z</b>]
(Polar coordinates (theta,r)) <b><br>
−Jx</b><i>x-scale</i>[<b>d</b>|<b>l</b>|<b>p</b><i>pow</i>|<b>t</b>|<b>T</b>][<i>/y-scale</i>[<b>d</b>|<b>l</b>|<b>p</b><i>pow</i>|<b>t</b>|<b>T</b>]]
(Linear, log, and power scaling)</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em"><b>−L</b></p></td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em">Pass all records whose location
is within <i>dist</i> of any of the line segments in the
ASCII multiple-segment file <i>linefile</i>. If <i>dist</i>
is zero then the 2nd column of each sub-header in the
<i>ptfile</i> must have each lines’s individual
distance value. Distances are Cartesian and in user units;
specify <b>−fg</b> to indicate spherical distances in
km. If <b><A HREF="gmtdefaults.html#ELLIPSOID">ELLIPSOID</A></b> is spherical then geodesics become
great circles (faster to compute than geodesic).
Alternatively, if <b>−R</b> and <b>−J</b> are
used then geographic coordinates are projected to map
coordinates (in cm, inch, m, or points, as determined by
<b><A HREF="gmtdefaults.html#MEASURE_UNIT">MEASURE_UNIT</A></b>) before Cartesian distances are compared
to <i>dist</i>. Use <b>−Lp</b> to ensure only points
whose orthogonal projections onto the nearest line-segment
fall within the segments endpoints [Default considers points
"beyond" the line’s endpoints.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p><b>−N</b></p></td>
<td width="8%"></td>
<td width="78%">
<p>Pass all records whose location is inside specified
geographical features. Specify if records should be skipped
(s) or kept (k) using 1 of 2 formats:</p></td></tr>
</table>
<p style="margin-left:22%;"><b>−N</b><i>wet/dry</i>.
<b><br>
−N</b><i>ocean/land/lake/island/pond</i>. <br>
Append <b>o</b> to let points exactly on feature boundaries
be considered outside the feature [Default is inside].
[Default is s/k/s/k/s (i.e., s/k), which passes all points
on dry land].</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em"><b>−R</b></p></td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em"><i>xmin</i>, <i>xmax</i>,
<i>ymin</i>, and <i>ymax</i> specify the Region of interest.
For geographic regions, these limits correspond to <i>west,
east, south,</i> and <i>north</i> and you may specify them
in decimal degrees or in [+-]dd:mm[:ss.xxx][W|E|S|N] format.
Append <b>r</b> if lower left and upper right map
coordinates are given instead of w/e/s/n. The two shorthands
<b>−Rg</b> and <b>−Rd</b> stand for global
domain (0/360 and -180/+180 in longitude respectively, with
-90/+90 in latitude). Alternatively, specify the name of an
existing grid file and the <b>−R</b> settings (and
grid spacing, if applicable) are copied from the grid. For
calendar time coordinates you may either give (a) relative
time (relative to the selected <b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b> and in the
selected <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b>; append <b>t</b> to
<b>−JX</b>|<b>x</b>), or (b) absolute time of the form
[<i>date</i>]<b>T</b>[<i>clock</i>] (append <b>T</b> to
<b>−JX</b>|<b>x</b>). At least one of <i>date</i> and
<i>clock</i> must be present; the <b>T</b> is always
required. The <i>date</i> string must be of the form
[-]yyyy[-mm[-dd]] (Gregorian calendar) or yyyy[-Www[-d]]
(ISO week calendar), while the <i>clock</i> string must be
of the form hh:mm:ss[.xxx]. The use of delimiters and their
type and positions must be exactly as indicated (however,
input, output and plot formats are customizable; see
<b><A HREF="gmtdefaults.html">gmtdefaults</A></b>). If no map projection is supplied we
implicitly set <b>−Jx</b> 1. Note: only supply
<b>−J</b> when your <b>−R</b> is indicating a
rectangular region in the projected coordinates (i.e., an
oblique projection).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−V</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Selects verbose mode, which will send progress reports
to stderr [Default runs "silently"].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−Z</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Pass all records whose 3rd column (z) lies within the
given range. Input file must have at least three columns. To
indicate no limit on min or max, specify a hyphen (-). If
your 3rd column is absolute time then remember to supply
<b>−f</b> 2T.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−:</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Toggles between (longitude,latitude) and
(latitude,longitude) input and/or output. [Default is
(longitude,latitude)]. Append <b>i</b> to select input only
or <b>o</b> to select output only. [Default affects
both].</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−bi</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Selects binary input. Append <b>s</b> for single
precision [Default is <b>d</b> (double)]. Uppercase <b>S</b>
or <b>D</b> will force byte-swapping. Optionally, append
<i>ncol</i>, the number of columns in your binary input file
if it exceeds the columns needed by the program. Or append
<b>c</b> if the input file is netCDF. Optionally, append
<i>var1</i><b>/</b><i>var2</i><b>/</b><i>...</i> to specify
the variables to be read. [Default is 2 input columns].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−bo</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Selects binary output. Append <b>s</b> for single
precision [Default is <b>d</b> (double)]. Uppercase <b>S</b>
or <b>D</b> will force byte-swapping. Optionally, append
<i>ncol</i>, the number of desired columns in your binary
output file. [Default is same as input].</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−f</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Special formatting of input and/or output columns (time
or geographical data). Specify <b>i</b> or <b>o</b> to make
this apply only to input or output [Default applies to
both]. Give one or more columns (or column ranges) separated
by commas. Append <b>T</b> (absolute calendar time),
<b>t</b> (relative time in chosen <b><A HREF="gmtdefaults.html#TIME_UNIT">TIME_UNIT</A></b> since
<b><A HREF="gmtdefaults.html#TIME_EPOCH">TIME_EPOCH</A></b>), <b>x</b> (longitude), <b>y</b>
(latitude), or <b>f</b> (floating point) to each column or
column range item. Shorthand
<b>−f</b>[<b>i</b>|<b>o</b>]<b>g</b> means
<b>−f</b>[<b>i</b>|<b>o</b>]0<b>x</b>,1<b>y</b>
(geographic coordinates).</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p><b>−m</b></p></td>
<td width="7%"></td>
<td width="78%">
<p>Multiple segment file(s). Segments are separated by a
special record. For ASCII files the first character must be
<i>flag</i> [Default is ’>’]. For binary
files all fields must be NaN and <b>−b</b> must set
the number of output columns explicitly. By default the
<b>−m</b> setting applies to both input and output.
Use <b>−mi</b> and <b>−mo</b> to give separate
settings to input and output. The <b>−m</b> option
make sure that segment headers in the input files are copied
to output, but it has no effect on the data selection.
Selection is always done point by point, not by segment.</p></td></tr>
</table>
<h2>ASCII FORMAT PRECISION
<a name="ASCII FORMAT PRECISION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">The ASCII
output formats of numerical data are controlled by
parameters in your .gmtdefaults4 file. Longitude and
latitude are formatted according to
<b><A HREF="gmtdefaults.html#OUTPUT_DEGREE_FORMAT">OUTPUT_DEGREE_FORMAT</A></b>, whereas other values are
formatted according to <b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b>. 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 (<b>−bo</b> if
available) or specify more decimals using the
<b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b> setting. <br>
This note applies to ASCII output only in combination with
binary or netCDF input or the <b>−:</b> option. See
also the note below.</p>
<h2>NOTE ON PROCESSING ASCII INPUT RECORDS
<a name="NOTE ON PROCESSING ASCII INPUT RECORDS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">Unless you are
using the <b>−:</b> option, selected ASCII input
records are copied verbatim to output. That means that
options like <b>−foT</b> and settings like
<b><A HREF="gmtdefaults.html#D_FORMAT">D_FORMAT</A></b> and <b><A HREF="gmtdefaults.html#OUTPUT_DEGREE_FORMAT">OUTPUT_DEGREE_FORMAT</A></b> will not
have any effect on the output. On the other hand, it allows
selecting records with diverse content, including character
strings, quoted or not, comments, and other non-numerical
content.</p>
<h2>NOTE ON DISTANCES
<a name="NOTE ON DISTANCES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">If options
<b>−C</b> or <b>−L</b> are selected then
distances are Cartesian and in user units; use
<b>−fg</b> to imply spherical distances in km and
geographical (lon, lat) coordinates. Alternatively, specify
<b>−R</b> and <b>−J</b> to measure projected
Cartesian distances in map units (cm, inch, m, or points, as
determined by <b><A HREF="gmtdefaults.html#MEASURE_UNIT">MEASURE_UNIT</A></b>). <br>
This program has evolved over the years. Originally, the
<b>−R</b> and <b>−J</b> were mandatory in order
to handle geographic data, but now there is full support for
spherical calculations. Thus, <b>−J</b> should only be
used if you want the tests to be applied on projected data
and not the original coordinates. If <b>−J</b> is used
the distances given via <b>−C</b> and <b>−L</b>
are projected distances.</p>
<h2>EXAMPLES
<a name="EXAMPLES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">To extract the
subset of data set that is within 300 km of any of the
points in pts.d but more than 100 km away from the lines in
lines.d, run</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
lonlatfile <b>−fg −C</b> 300/pts.d
<b>−L</b> 100/lines.d <b>−Il</b> > subset</p>
<p style="margin-left:11%; margin-top: 1em">Here, you must
specify <b>−fg</b> so the program knows you are
processing geographical data (otherwise 300 would be
interpreted as Cartesian distance in x-y units instead of
km).</p>
<p style="margin-left:11%; margin-top: 1em">To keep all
points in data.d within the specified region, except the
points on land (as determined by the high-resolution
coastlines), use</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
data.d <b>−R</b> 120/121/22/24 <b>−Dh
−Nk</b>/<b>s</b> > subset</p>
<p style="margin-left:11%; margin-top: 1em">To return all
points in quakes.d that are inside the spherical polygon
lonlatpath.d, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
quakes.d <b>−F</b> lonlatpath.d <b>−fg</b> >
subset1</p>
<p style="margin-left:11%; margin-top: 1em">To return all
points in stations.d that are within 5 cm of the point in
origin.d for a certain projection, try</p>
<p style="margin-left:11%; margin-top: 1em"><b>gmtselect</b>
stations.d <b>−F</b> origin.d <b>−R</b>
20/50/-10/20 <b>−JM</b> 20c > subset2</p>
<h2>GSHHS INFORMATION
<a name="GSHHS INFORMATION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">The coastline
database is GSHHS which is compiled from two sources: World
Vector Shorelines (WVS) and CIA World Data Bank II (WDBII).
In particular, all level-1 polygons (ocean-land boundary)
are derived from the more accurate WVS while all higher
level polygons (level 2-4, representing land/lake,
lake/island-in-lake, and
island-in-lake/lake-in-island-in-lake boundaries) are taken
from WDBII. Much processing has taken place to convert WVS
and WDBII data into usable form for <b><A HREF="GMT.html">GMT</A></b>: assembling
closed polygons from line segments, checking for duplicates,
and correcting for crossings between polygons. The area of
each polygon has been determined so that the user may choose
not to draw features smaller than a minimum area (see
<b>−A</b>); one may also limit the highest
hierarchical level of polygons to be included (4 is the
maximum). The 4 lower-resolution databases were derived from
the full resolution database using the Douglas-Peucker
line-simplification algorithm. The classification of rivers
and borders follow that of the WDBII. See the <b><A HREF="GMT.html">GMT</A></b>
Cookbook and Technical Reference Appendix K for further
details.</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><i><A HREF="gmtdefaults.html">gmtdefaults</A></i>(1),
<i><A HREF="GMT.html">GMT</A></i>(1), <i><A HREF="grdlandmask.html">grdlandmask</A></i>(1), <i><A HREF="pscoast.html">pscoast</A></i>(1)</p>
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