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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>
<a name="NAME"></a>
<h2>NAME</h2>
<p style="margin-left:11%; margin-top: 1em">gmtselect
− Select data subsets based on multiple spatial
criteria</p>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</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>cflrs</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>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</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>
<a name="OPTIONS"></a>
<h2>OPTIONS</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 style="margin-top: 1em" valign="top"><b>−A</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−C</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−D</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−F</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−H</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−I</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">Reverses the sense
of the test for each of the criteria specified:</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>c</b> select records NOT inside any
point’s circle of influence.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>f</b> select records NOT inside any of
the polygons.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>l</b> select records NOT within the
specified distance of any line.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>r</b> select records NOT inside the
specified rectangular region.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>s</b> select records NOT considered
inside as specified by <b>−A −D
−N</b>.</p> </td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>z</b> select records NOT within the
range specified by <b>−Z</b>.</p></td>
</table>
<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" valign="top"><b>−J</b></p> </td>
<td width="8%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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>
</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
IV) <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" valign="top"><b>−L</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%">
<p style="margin-top: 1em" valign="top"><b>−N</b></p> </td>
<td width="4%"></td>
<td width="82%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>−N</b><i>wet/dry</i>.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="3%"></td>
<td width="4%"></td>
<td width="82%">
<p valign="top"><b>−N</b><i>ocean/land/lake/island/pond</i>.</p> </td>
</table>
<p style="margin-left:22%;">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" valign="top"><b>−R</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top"><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.</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−V</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">Selects verbose
mode, which will send progress reports to stderr [Default
runs "silently"].</p></td>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−Z</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−:</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−bi</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−bo</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−f</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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 valign="top" align="left">
<td width="11%"></td>
<td width="4%">
<p style="margin-top: 1em" valign="top"><b>−m</b></p> </td>
<td width="7%"></td>
<td width="78%">
<p style="margin-top: 1em" valign="top">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>
</table>
<a name="ASCII FORMAT PRECISION"></a>
<h2>ASCII FORMAT PRECISION</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>
<a name="NOTE ON PROCESSING ASCII INPUT RECORDS"></a>
<h2>NOTE ON PROCESSING ASCII INPUT RECORDS</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>
<a name="NOTE ON DISTANCES"></a>
<h2>NOTE ON DISTANCES</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>
<a name="EXAMPLES"></a>
<h2>EXAMPLES</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>
<a name="GSHHS INFORMATION"></a>
<h2>GSHHS INFORMATION</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>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</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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