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gmtinfo(1)                            GMT                           gmtinfo(1)




NAME

       gmtinfo - Return information about data tables


SYNOPSIS

       gmtinfo [ table ] [  -Aa|f|s ] [  -C ] [  -D[dx[/dy]] ] [  -EL|l|H|hcol
       ] [  -F[i|d|t] ] [  -I[p|f|s]dx[/dy[/dza|] ] [  -L ] [   -S[x][y]  ]  [
       -Tdz[+ccol] ] [  -V[level] ] [ -bibinary ] [ -dinodata ] [ -eregexp ] [
       -fflags ] [ -ggaps ] [ -hheaders ] [ -iflags ] [ -oflags ]  [  -r  ]  [
       -:[i|o] ]

       Note:  No  space  is allowed between the option flag and the associated
       arguments.


DESCRIPTION

       gmtinfo reads its standard input [or from files] and finds the  extreme
       values  in each of the columns. It recognizes NaNs and will print warn-
       ings if the number of columns vary from record to record. As an option,
       gmtinfo will find the extent of the first n columns rounded up and down
       to the nearest multiple of the supplied increments.  By  default,  this
       output  will be in the form -Rw/e/s/n which can be used directly in the
       command line for other programs (hence only dx and dy are  needed),  or
       the  output  will  be  in  column form for as many columns as there are
       increments  provided.  A   similar   option   (-T)   will   provide   a
       -Tzmin/zmax/dz string for makecpt.


REQUIRED ARGUMENTS

       None.


OPTIONAL ARGUMENTS

       table  One  or  more ASCII (or binary, see -bi[ncols][type]) data table
              file(s) holding a number of data columns. If no tables are given
              then we read from standard input.

       -Aa|f|s
              Specify  how  the  range  should be reported. Choose -Aa for the
              range of all files combined, -Af to report the  range  for  each
              file  separately,  and  -As to report the range for each segment
              (in multisegment files) separately. [Default is -Aa].

       -C     Report  the  min/max  values  per  column  in  separate  columns
              [Default  uses  <min/max> format]. When used, users may also use
              -o to limit which output columns should be reported [all].

       -D     Modifies results obtained by -I by shifting the region to better
              align with the center of the data.  Optionally, append granular-
              ity for this shift [Default performs an exact shift].

       -EL|l|H|hcol
              Returns the record whose column col contains the minimum (l)  or
              maximum  (h)  value. Upper case (L|H) works on absolute value of
              the data. In case of multiple matches, only the first record  is
              returned.  If col is not specified we default to the last column
              in the data.

       -F[i|d|t] ]
              Returns the counts of various records depending on the  appended
              mode: i returns a single record with the total number of tables,
              segments, data records, header records, and overall records.  In
              contrast,  d returns information for each segment in the virtual
              data set: tbl_number, seg_number, n_rows, start_rec, stop_rec. t
              does  the  same but honors the input table organization and thus
              resets seg_number, start_rec, stop_rec at the start of each  new
              table.

       -I[p|f|s]dx[/dy[/dza|]
              Report  the min/max of the first n columns to the nearest multi-
              ple of the provided increments (separate  the  n  increments  by
              slashes), and output results in the form -Rw/e/s/n (unless -C is
              set). If only one increment is given we also use it for the sec-
              ond  column  (for  backwards  compatibility).  To  override this
              behavior, use -Ipdx. If the input x- and y-coordinates all  have
              the  same  phase shift relative to the dx and dy increments then
              we use those phase shifts in determining the region, and you may
              use  -r  to switch from gridline-registration to pixel-registra-
              tion.  For irregular data both phase shifts are set to 0 and the
              -r  is  ignored.   Use  -Ifdx[/dy]  to report an extended region
              optimized to give grid dimensions for fastest  results  in  pro-
              grams  using  FFTs.  Use -Isdx[/dy] to report an extended region
              optimized to give grid dimensions for fastest  results  in  pro-
              grams like surface.  If dx is given as - then the actual min/max
              of the input is given in the -R string.

       -L     Determines common limits across tables (-Af) or segments  (-As).
              If  used  with  -I  it  will round inwards so that the resulting
              bounds lie within the actual data domain.

       -S[x][y]
              Add extra space for error bars. Useful together with  -I  option
              and when later plotting with psxy -E. -Sx leaves space for hori-
              zontal error bars using the values  in  third  (2)  column.  -Sy
              leaves  space  for vertical error bars using the values in third
              (2) column. -S or -Sxy leaves space for both  error  bars  using
              the values in third and fourth (2 and 3) columns.

       -Tdz[+ccol]
              Report  the  min/max  of  the first (0ath) column to the nearest
              multiple of dz and output this as the string -Tzmin/zmax/dz.  To
              use  another  column,  append  +ccol.  Only  works  when  -I  is
              selected.

       -V[level] (more a|)
              Select verbosity level [c].

       -bi[ncols][t] (more a|)
              Select native binary input. [Default is 2 input columns].

       -dinodata (more a|)
              Replace input columns that equal nodata with NaN.

       -e[~]^<i>apattern^<i>a | -e[~]/regexp/[i] (more a|)
              Only accept data records that match the given pattern.

       -f[i|o]colinfo (more a|)
              Specify data types of input and/or output columns.

       -g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] (more a|)
              Determine data gaps and line breaks.

       -h[i|o][n][+c][+d][+rremark][+rtitle] (more a|)
              Skip or produce header record(s).

       -icols[+l][+sscale][+ooffset][,^<i>a|] (more a|)
              Select input columns and transformations (0 is first column).

       -ocols[,a|] (more a|)
              Select output columns (0 is first column).

       -r (more a|)
              Set pixel node registration [gridline].

       -:[i|o] (more a|)
              Swap 1st and 2nd column on input and/or output.

       -^ or just -
              Print a short message about the  syntax  of  the  command,  then
              exits (NOTE: on Windows just use -).

       -+ or just +
              Print  an extensive usage (help) message, including the explana-
              tion of any module-specific  option  (but  not  the  GMT  common
              options), then exits.

       -? or no arguments
              Print a complete usage (help) message, including the explanation
              of all options, then exits.


ASCII FORMAT PRECISION

       The ASCII output formats of numerical data are controlled by parameters
       in  your  gmt.conf file. Longitude and latitude are formatted according
       to  FORMAT_GEO_OUT,  absolute  time  is  under  the  control  of   FOR-
       MAT_DATE_OUT  and FORMAT_CLOCK_OUT, whereas general floating point val-
       ues are formatted according to FORMAT_FLOAT_OUT. Be aware that the for-
       mat  in effect can lead to loss of precision in ASCII 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 FORMAT_FLOAT_OUT  set-
       ting.


EXAMPLES

       To find the extreme values in the file ship_gravity.xygd:

              gmt info ship_gravity.xygd

       Output should look like

              ship_gravity.xygd: N = 6992 <326.125/334.684> <-28.0711/-8.6837> <-47.7/177.6> <0.6/3544.9>

       To  find the extreme values in the file track.xy to the nearest 5 units
       but shifted to within 1 unit of the data center, and use this region to
       draw a line using psxy, run

              gmt psxy `gmt info -I5 -D1 track.xy` track.xy -Jx1 -B5 -P > track.ps

       To  find  the  min  and max values for each of the first 4 columns, but
       rounded to integers, and return the result individually for  each  data
       file, use

              gmt info profile_*.txt -C -I1/1/1/1

       Given  seven  profiles with different start and stop positions, we want
       to find a range of positions, with increment of 5, that are  common  to
       all the profiles.  We use

              gmt info profile_[123567].txt -L -I5

       The  file magprofs.txt contains a number of magnetic profiles stored as
       separate data segments.  We need to know how many  segments  there  are
       and use

              gmt info magprofs.txt -Fi


BUGS

       The  -I  option does not yet work properly with time series data (e.g.,
       -f0T). Thus, such variable intervals as months and years are not calcu-
       lated.  Instead, specify your interval in the same units as the current
       setting of TIME_UNIT.


SEE ALSO

       gmt(1), gmtconvert(1), psxy(1)


COPYRIGHT

       2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe



5.4.2                            Jun 24, 2017                       gmtinfo(1)

gmt5 5.4.2 - Generated Wed Jun 28 16:27:24 CDT 2017
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