Provided by: gmt_4.5.11-1build1_amd64 bug

NAME

       sample1d - Resampling of 1-D data sets

SYNOPSIS

       sample1d  infile  [  -Fl|a|c|n  ] [ -H[i][nrec] ] [ -Ixinc ] [ -Nknotfile ] [ -Sxstart ] [
       -Tx_col ] [ -V ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [ -f[i|o]colinfo ] [ -m[i|o][flag]
       ]

DESCRIPTION

       sample1d reads a multi-column ASCII [or binary] data set from file [or standard input] and
       interpolates 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) variable.  Equidistant or arbitrary sampling can be selected.  All columns are
       resampled  based  on  the  new  sampling  interval.   Several  interpolation  schemes  are
       available.  Extrapolation outside the range of the input data is not supported.

       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 arguments.

       -F     Choose  from  l  (Linear),  a  (Akima  spline), c (natural cubic spline), and n (no
              interpolation: nearest point)  [Default  is  -Fa].   You  may  change  the  default
              interpolant; see INTERPOLANT in your .gmtdefaults4 file.

       -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.

       -I     xinc defines the sampling interval. [Default is the separation  between  the  first
              and second abscissa point in the infile]

       -N     knotfile  is an optional ASCII file with the x locations where the data set will be
              resampled in the first column.  Note: if -H is selected it applies to  both  infile
              and knotfile.

       -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)].

       -V     Selects verbose mode, which will send progress  reports  to  stderr  [Default  runs
              "silently"].

       -bi    Selects  binary  input.   Append  s  for  single precision [Default is d (double)].
              Uppercase S or D will force byte-swapping.  Optionally, append ncol, the number  of
              columns  in your binary input file if it exceeds the columns needed by the program.
              Or append c if the input  file  is  netCDF.  Optionally,  append  var1/var2/...  to
              specify the variables to be read.  [Default is 2 (or at least the number of columns
              implied by -T)].

       -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.  [Default is same as input].

       -f     Special formatting of input and/or output  columns  (time  or  geographical  data).
              Specify  i  or  o  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  T
              (absolute calendar time), t (relative time in chosen TIME_UNIT since TIME_EPOCH), x
              (longitude), y (latitude), or f (floating point) to each  column  or  column  range
              item.  Shorthand -f[i|o]g means -f[i|o]0x,1y (geographic coordinates).

       -m     Multiple  segment  file(s).  Segments are separated by a special record.  For ASCII
              files the first character must be flag [Default is  '>'].   For  binary  files  all
              fields  must  be  NaN  and -b must set the number of output columns explicitly.  By
              default the -m setting applies to both input and output.  Use -mi and -mo  to  give
              separate settings to input and output.

ASCII FORMAT PRECISION

       The  ASCII  output  formats  of  numerical  data  are  controlled  by  parameters  in your
       .gmtdefaults4   file.    Longitude   and   latitude    are    formatted    according    to
       OUTPUT_DEGREE_FORMAT,  whereas other values are formatted according to D_FORMAT.  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 (-bo if available) or specify more decimals using  the
       D_FORMAT setting.

CALENDAR TIME SAMPLING

       If  the  abscissa  are  calendar  times  then you must use the -f option to indicate this.
       Furthermore, -I then expects an increment in the current TIME_UNIT units.   There  is  not
       yet support for variable intervals such as months.

EXAMPLES

       To        resample        the        file       profiles.tdgmb,       which       contains
       (time,distance,gravity,magnetics,bathymetry) records, at 1km equidistant  intervals  using
       Akima's spline, use

       sample1d profiles.tdgmb -I 1 -Fa -T 1 > 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 interpolation, use

       sample1d depths.dt -N grav_pos.dg -Fc > new_depths.dt

SEE ALSO

       GMT(1), filter1d(1)