GMTCONVERT(1) Generic Mapping Tools GMTCONVERT(1)NAMEgmtconvert - Converts, Pastes, and/or Extracts columns from ASCII and
binary 1-D tables
SYNOPSISgmtconvert [ inputfiles ] [ -A ] [ -D[template] ] [ -E[f|l] ] [ -Fcols
] [ -H[i][nrec] ] [ -L ] [ -I ] [ -N ] [ -S[~]"search string" ] [ -V ]
[ -:[i|o] ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [ -f[i|o]colinfo ] [
-g[a]x|y|d|X|Y|D|[col]z[+|-]gap[u] ] [ -m[i|o][flag] ]
DESCRIPTIONgmtconvert reads its standard input [or inputfiles] and writes out the
desired information to standard output. It can do a combination of
three things: (1) convert between binary and ASCII data tables, (2)
paste corresponding records from multiple files into a single file, (3)
extract a subset of the columns, (4) only extract segments whose header
matches a text pattern search, (5) just list all multisegment headers
and no data records, and (6) extract first and last data record for
each segment. Input (and hence output) may have multiple subheaders if
-m is selected, and ASCII tables may have regular headers as well.
datafile(s)
ASCII (or binary, see -bi) file(s) holding a number of data col‐
umns.
OPTIONS-A The records from the input files should be pasted horizontally,
not appended vertically. [Default processes one file at the
time]. Note for binary input, all the files you want to paste
must have the same number of columns (as set with -bi).
-D For multiple segment data, dump each segment to a separate out‐
put file [Default writes a multiple segment file to stdout].
Append a format template for the individual file names; this
template must contain a C format specifier that can format an
integer argument (the segment number); this is usually %d but
could be %8.8d which gives leading zeros, etc. [Default is gmt‐
convert_segment_%d.d].
-E Only extract the first and last record for each segment of
interest [Default extracts all records]. Optionally, append f
or l to only extract the first or last record of each segment,
respectively.
-F Give a comma-separated list of desired columns or ranges (0 is
first column) [Default outputs all 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.
-I Invert the order of rows, i.e., output the final records in
reverse order, starting with the last and ending up with the
first input row [Default goes forward].
-L Only output a listing of all multisegment header records and no
data records (requires -m and ASCII data).
-N Do not write records that only contain NaNs in every field
[Default writes all records].
-S Only output those segments whose header record contains the
specified text string. To reverse the search, i.e., to output
segments whose headers do not contain the specified pattern, use
-S~. Should your pattern happen to start with ~ you need to
escape this character with a backslash [Default output all seg‐
ments].
-V Selects verbose mode, which will send progress reports to stderr
[Default runs "silently"].
-: 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].
-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.
-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 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).
-g Examine the spacing between consecutive data points in order to
impose breaks in the line. Append x|X or y|Y to define a gap
when there is a large enough change in the x or y coordinates,
respectively, or d|D for distance gaps; use upper case to calcu‐
late gaps from projected coordinates. For gap-testing on other
columns use [col]z; if col is not prepended the it defaults to 2
(i.e., 3rd column). Append [+|-]gap and optionally a unit u.
Regarding optional signs: -ve means previous minus current col‐
umn value must exceed |gap to be a gap, +ve means current minus
previous column value must exceed gap, and no sign means the
absolute value of the difference must exceed gap. For geo‐
graphic data (x|y|d), the unit u may be meter [Default], kilome‐
ter, miles, or nautical miles. For projected data (X|Y|D),
choose from inch, centimeter, meter, or points [Default unit set
by MEASURE_UNIT]. Note: For x|y|z with time data the unit is
instead controlled by TIME_UNIT. Repeat the option to specify
multiple criteria, of which any can be met to produce a line
break. Issue an additional -ga to indicate that all criteria
must be met instead.
-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 convert the binary file test.b (single precision) with 4 columns to
ASCII:
gmtconvert test.b -bis 4 > test.dat
To convert the multiple segment ASCII table test.d to a double preci‐
sion binary file:
gmtconvert test.d -m -bo > test.b
You have an ASCII table with 6 columns and you want to plot column 5
versus column 0. Try
gmtconvert table.d -F 5,0 | psxy ...
If the file instead is the binary file results.b which has 9 single-
precision values per record, we extract the last column and columns 4-6
and write ASCII with the command
gmtconvert results.b -F 8,4-6 -bi9s | psxy ...
You want to plot the 2nd column of a 2-column file left.d versus the
first column of a file right.d:
gmtconvert left.d right.d -A -F 1,2 | psxy ...
To extract all segments in the file big_file.d whose headers contain
the string "RIDGE AXIS", try
gmtconvert big_file.d -m -S"RIDGE AXIS" > subset.d
SEE ALSOGMT(1), minmax(1)GMT 4.5.14 1 Nov 2015 GMTCONVERT(1)
