X2SYS_DATALIST(1) Generic Mapping Tools X2SYS_DATALIST(1)NAMEx2sys_datalist - A generic data-extractor for ASCII or binary files
SYNOPSISx2sys_datalisttrack(s)-TTAG [ -A ] [ -Fname1,name2,... ] [
-H[i][nrec] ] [ -L[corrtable] ] [ -Rwest/east/south/north[r] ] [ -S ]
[ -V ] [ -bo[s|S|d|D[ncol]|c[var1/...]] ] [ -m[flag] ]
DESCRIPTIONx2sys_datalist reads one or more files and produces a single ASCII [or
binary] table. The files can be of any format, which must be described
and passed with the -T option. You may limit the output to a geo‐
graphic region, and insist that the output from several files be sepa‐
rated by a multiple segment header. Only the named data fields will be
output [Default selects all columns].
tracks Can be one or more ASCII, native binary, or COARDS netCDF 1-D
data files. To supply the data files via a text file with a
list of tracks (one per record), specify the name of the track
list after a leading equal-sign (e.g., =tracks.lis). If the
names are missing their file extension we will append the suffix
specified for this TAG. Track files will be searched for first
in the current directory and second in all directories listed in
$X2SYS_HOME/TAG/TAG_paths.txt (if it exists). [If $X2SYS_HOME is
not set it will default to $GMT_SHAREDIR/x2sys]. (Note: MGD77
files will also be looked for via MGD77_HOME/mgd77_paths.txt and
*.gmt files will be searched for via $GMT_SHAREDIR/mgg/gmt‐
file_paths).
-T Specify the x2sys TAG which tracks the attributes of this data
type.
OPTIONS
No space between the option flag and the associated arguments.
-A Eliminate COEs by distributing the COE between the two tracks in
proportion to track weight. These (dist, adjustment) spline
knots files for each track and data column are called track.col‐
umn.adj and are expected to be in the $X2SYS_HOME/TAG directory.
The adjustments are only applied if the corresponding adjust
file can be found [No residual adjustments]
-F Give a comma-separated sub-set list of column names defined in
the definition file. [Default selects all data columns].
-H Input file(s) has header record(s). If used, the default number
of header records is N_HEADER_RECS. Use -Hi 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.
-L Apply optimal corrections to columns where such corrections are
available. Append the correction table to use [Default uses the
correction table TAG_corrections.txt which is expected to reside
in the $X2SYS_HOME/TAG directory]. For the format of this file,
see CORRECTIONS below.
-R west, east, south, and north specify the Region of interest, and
you may specify them in decimal degrees or in
[+-]dd:mm[:ss.xxx][W|E|S|N] format. Append r if lower left and
upper right map coordinates are given instead of w/e/s/n. The
two shorthands -Rg and -Rd 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
-R settings (and grid spacing, if applicable) are copied from
the grid. For Cartesian data just give xmin/xmax/ymin/ymax.
This option limits the COEs to those that fall inside the speci‐
fied domain.
-S Suppress output records where all the data columns are NaN
[Default will output all records].
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-bo Selects binary output. Append s for single precision [Default
is d (double)]. Uppercase S or D will force byte-swapping.
Optionally, append ncol, the number of desired columns in your
binary output file.
-m Output a multisegment header between data from each track. Note
this option does not imply anything about the input file; that
information is conveyed via the system tag (-T).
EXAMPLES
To extract all data from the old-style MGG supplement file c2104.gmt,
recognized by the tag GMT:
x2sys_datalist c2104.gmt -T GMT > myfile
To make lon,lat, and depth input for blockmean and surface using all
the files listed in the file tracks.lis and define by the tag TRK, but
only the data that are inside the specified area, and make output
binary, run
x2sys_datalist =tracks.lis -T TRK -F lon,lat,depth -R-40/-30/25/35 -bo
> alltopo_bin.xyz
CORRECTIONS
The correction table is an ASCII file with coefficients and parameters
needed to carry out corrections. This table is usually produced by
x2sys_solve. Comment records beginning with # are allowed. All cor‐
rection records are of the form
trackID observation correction
where trackID is the track name, observation is one of the abbrevia‐
tions for an observed field contained in files under this TAG, and cor‐
rection consists of one or more white-space-separated terms that will
be subtracted from the observation before output. Each term must have
this exact syntax:
factor[*[function]([scale](abbrev[-origin]))[^power]]
where terms in brackets are optional (the brackets themselves are not
used but regular parentheses must be used exactly as indicated). No
spaces are allowed except between terms. The factor is the amplitude of
the basis function, while the optional function can be one of sin, cos,
or exp. The optional scale and origin can be used to translate the
argument (before giving it to the optional function). The argument
abbrev is one of the abbreviations for columns known to this TAG. How‐
ever, it can also be one of the three auxiliary terms dist (for along-
track distances), azim for along-track azimuths, and vel (for along-
track speed); these are all sensitive to the -C and -N settings used
when defining the TAB; furthermore, vel requires time to be present in
the data. If origin is given as T it means that we should replace it
with the value of abbrev for the very first record in the file (this is
usually only done for time). If the first data record entry is NaN we
revert origin to zero. Optionally, raise the entire expression to the
given power, before multiplying by factor. The following is an example
of fictitious corrections to the track ABC, implying the z column
should have a linear trend removed, the field obs should be corrected
by a strange dependency on latitude, weight needs to have 1 added
(hence correction is given as -1), and fuel should be reduced by a lin‐
ear distance term:
ABC z 7.1 1e-4*((time-T))
ABC obs 0.5*exp(-1e-3(lat))^1.5
ABC weight -1
ABC fuel 0.02*((dist))
SEE ALSOblockmean(1), GMT(1), surface(1), x2sys_init(1), x2sys_datalist(1),
x2sys_get(1), x2sys_list(1), x2sys_put(1), x2sys_report(1),
x2sys_solve(1)GMT 4.5.14 1 Nov 2015 X2SYS_DATALIST(1)
