MINMAX(1) Generic Mapping Tools MINMAX(1)NAMEminmax - Find extreme values in data tables
SYNOPSISminmax [ files] [ -C ] [ -EL|l|H|hcol ] [ -H[i][nrec] ] [
-I[p]dx[/dy[/dz...] ] [ -S[x][y] ] [ -Tdz[/col] ] [ -:[i|o] ] [
-bi[s|S|d|D[ncol]|c[var1/...]] ] [ -f[i|o]colinfo ] [ -m[i|o][flag] ]
DESCRIPTIONminmax 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, minmax 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.
xyzfile
ASCII [or binary, see -b] file(s) holding a fixed number of data
columns.
OPTIONS-C Report the min/max values per column in separate columns
[Default uses <min/max> format].
-E 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.
-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 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
second column (for backwards compatibility). To override this
behaviour, use -Ipdx.
-S Add extra space for error bars. Useful together with -I option
and when later plotting with psxy -E.-Sx leaves space for hor‐
izontal 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.
-T Report the min/max of the first (0'th) column to the nearest
multiple of dz and output this in the form -Tzmin/zmax/dz. To
use another column, append /col.
-: Toggles between (longitude,latitude) and (latitude,longitude)
input and/or output. [Default is (longitude,latitude)]. Append
i to select input only or o to select output only. [Default
affects both]. Only works when -I is selected.
-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 input columns].
-f Special formatting of input and/or output columns (time or geo‐
graphical 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 (abso‐
lute 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 preci‐
sion, consider switching to binary output (-bo if available) or specify
more decimals using the D_FORMAT setting.
EXAMPLES
To find the extreme values in the file ship_gravity.xygd:
minmax 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
and use this region to draw a line using psxy, run
psxy `minmax -I 5 track.xy` track.xy -Jx 1 -B 5 -P > track.ps
To find the min and max values for each of the first 4 columns, but
rounded to integers, use
minmax junkfile -C -I 1/1/1/1
BUGS
The -I option does not yet work properly with time series data (e.g.,
-f 0T). Thus, such variable intervals as months and years are not cal‐
culated. Instead, specify your interval in the same units as the cur‐
rent setting of TIME_UNIT.
SEE ALSOGMT(1)GMT 4.5.14 1 Nov 2015 MINMAX(1)
