NAME
sample1d - Resampling of 1-D data sets
SYNOPSIS
sample1d infile [ -Fl|a|c ] [ -H[nrec] ] [ -Ixinc ] [
-M[flag] ] [ -Nknotfile ] [ -Sxstart ] [ -Tx-col] [
-bi[s][n] ] [ -bo[s] ]
DESCRIPTION
sample1d reads a multi-column ASCII [or binary] data set
from file [or standard input] and resamples the
timeseries/profile at locations where the user needs the
values. The user must provide the column number of the
independent (monotonically increasing or decreasing) vari-
able. Equidistant or arbitrary sampling can be selected.
All columns are resampled based on the new sampling inter-
val. Several interpolation schemes are available.
infile
This is a multi-column ASCII [of binary, see -b] file
with one column containing the independent variable
(which must be monotonically in/de-creasing) and the
remaining columns holding misc. data values. If no
file is provided, sample1d reads from standard input.
OPTIONS
No space between the option flag and the associated argu-
ments.
-F Choose from l (Linear), a (Akima spline), and c
(natural cubic spline) [Default is -Fa]. You may
change the default interpolant; see INTERPOLANT in your
.gmtdefaults file.
-H Input file(s) has Header record(s). Number of header
records can be changed by editing your .gmtdefaults
file. If used, GMT default is 1 header record.
-I xinc defines the sampling interval. [Default is the
separation between the first and second abcissa point
in the infile]
-M Multiple segment file. Segments are separated by a
record whose first character is flag. [Default is
'>'].
-N knotfile is an optional ASCII file with the x locations
where the data set will be resampled in the first
column
-S For equidistant sampling, xstart indicates the location
of the first output value. [Default is the smallest
even multiple of xinc inside the range of infile]
-T Sets the column number of the independent variable
[Default is 0 (first)].
-bi Selects binary input. Append s for single precision
[Default is double]. Append n for the number of
columns in the binary file(s). [Default is 2 (or at
least the number of columns implied by -T].
-bo Selects binary output. Append s for single precision
[Default is double].
EXAMPLES
To resample the file profiles.tdgmb, which contains
(time,distance,gravity,magnetics,bathymetry) records, at 1km
equidistant intervals using Akima's spline, try
sample1d profiles.tdgmb -I1 -Fa -T1 > profiles_equi_d.tdgmb
To resample the file depths.dt at positions listed in the
file grav_pos.dg, using a cubic spline for the interpola-
tion, try
sample1d depths.dt -Ngrav_pos.dg -Fc > new_depths.dt
SEE ALSO
gmt(l), filter1d(l)