1GMTCONVERT(1) Generic Mapping Tools GMTCONVERT(1)
2
6 gmtconvert - Converts, Pastes, and/or Extracts columns from ASCII and
7 binary 1-D tables
8
10 gmtconvert [ inputfiles ] [ -A ] [ -D[template] ] [ -E[f|l] ] [ -Fcols
11 ] [ -H[i][nrec] ] [ -L ] [ -I ] [ -M[i|o][flag] ] [ -N ] [ -S"search
12 string") ] [ -V ] [ -:[i|o] ] [ -b[i|o][s|S|d|D[ncol]|c[var1/...]] ] [
13 -f[i|o]colinfo ]
14
16 gmtconvert reads its standard input [or inputfiles] and writes out the
17 desired information to standard output. It can do a combination of
18 three things: (1) convert between binary and ASCII data tables, (2)
19 paste corresponding records from multiple files into a single file, (3)
20 extract a subset of the columns, (4) only extract segments whose header
21 matches a text pattern search, (5) just list all multisegment headers
22 and no data records, and (6) extract first and last data record for
23 each segment. Input (and hence output) may have multiple subheaders if
24 -M is selected, and ASCII tables may have regular headers as well.
25 datafile(s)
27 ASCII (or binary, see -bi) file(s) holding a number of data col‐
28 umns.
29
31 -A The records from the input files should be pasted horizontally,
32 not appended vertically. [Default processes one file at the
33 time]. Note for binary input, all the files you want to paste
34 must have the same number of columns (as set with -bi).
35 -D For multiple segment data, dump each segment to a separate out‐
37 put file [Default writes a multiple segment file to stdout].
38 Append a format template for the individual file names; this
39 template must contain a C format specifier that can format an
40 integer argument (the segment number); this is usually %d but
41 could be %8.8d which gives leading zeros, etc. [Default is gmt‐
42 convert_segment_%d.d].
43 -E Only extract the first and last record for each segment of
45 interest [Default extracts all records]. Optionally, append f
46 or l to only extract the first or last record of each segment,
47 respectively.
48 -F Give a comma-separated list of desired columns or ranges (0 is
50 first column) [Default outputs all columns].
51 -H Input file(s) has Header record(s). Number of header records
53 can be changed by editing your .gmtdefaults4 file. If used, GMT
54 default is 1 header record. Use -Hi if only input data should
55 have header records [Default will write out header records if
56 the input data have them]. Blank lines and lines starting with #
57 are always skipped.
58 -I Invert the order of rows, i.e., output the final records in
60 reverse order, starting with the last and ending up with the
61 first input row [Default goes forward].
62 -L Only output a listing of all multisegment header records and no
64 data records (requires -M and ASCII data).
65 -M Multiple segment file(s). Segments are separated by a special
67 record. For ASCII files the first character must be flag
68 [Default is '>']. For binary files all fields must be NaN and
69 -b must set the number of output columns explicitly. By default
70 the -M setting applies to both input and output. Use -Mi and
71 -Mo to give separate settings.
72 -N Do not write records that only contain NaNs in every field
74 [Default writes all records].
75 -S Only output those segments whose header record contains the
77 specified text string [Default output all segments].
78 -V Selects verbose mode, which will send progress reports to stderr
80 [Default runs "silently"].
81 -: Toggles between (longitude,latitude) and (latitude,longitude)
83 input and/or output. [Default is (longitude,latitude)]. Append
84 i to select input only or o to select output only. [Default
85 affects both].
86 -bi Selects binary input. Append s for single precision [Default is
88 d (double)]. Uppercase S or D will force byte-swapping.
89 Optionally, append ncol, the number of columns in your binary
90 input file if it exceeds the columns needed by the program. Or
91 append c if the input file is netCDF. Optionally, append
92 var1/var2/... to specify the variables to be read.
93 -bo Selects binary output. Append s for single precision [Default
95 is d (double)]. Uppercase S or D will force byte-swapping.
96 Optionally, append ncol, the number of desired columns in your
97 binary output file. [Default is same as input].
98 -f Special formatting of input and/or output columns (time or geo‐
100 graphical data). Specify i or o to make this apply only to
101 input or output [Default applies to both]. Give one or more
102 columns (or column ranges) separated by commas. Append T (abso‐
103 lute calendar time), t (relative time in chosen TIME_UNIT since
104 TIME_EPOCH), x (longitude), y (latitude), or f (floating point)
105 to each column or column range item. Shorthand -f[i|o]g means
106 -f[i|o]0x,1y (geographic coordinates).
107
109 The ASCII output formats of numerical data are controlled by parameters
110 in your .gmtdefaults4 file. Longitude and latitude are formatted
111 according to OUTPUT_DEGREE_FORMAT, whereas other values are formatted
112 according to D_FORMAT. Be aware that the format in effect can lead to
113 loss of precision in the output, which can lead to various problems
114 downstream. If you find the output is not written with enough preci‐
115 sion, consider switching to binary output (-bo if available) or specify
116 more decimals using the D_FORMAT setting.
117
119 To convert the binary file test.b (single precision) with 4 columns to
120 ASCII:
121 gmtconvert test.b -bis4 > test.dat
123 To convert the multiple segment ASCII table test.d to a double preci‐
125 sion binary file:
126 gmtconvert test.d -M -bo > test.b
128 You have an ASCII table with 6 columns and you want to plot column 5
130 versus column 0. Try
131 gmtconvert table.d -F5,0 | psxy ...
133 If the file instead is the binary file results.b which has 9 single-
135 precision values per record, we extract the last column and columns 4-6
136 and write ASCII with the command
137 gmtconvert results.b -F8,4-6 -bi9s | psxy ...
139 You want to plot the 2nd column of a 2-column file left.d versus the
141 first column of a file right.d:
142 gmtconvert left.d right.d -A -F1,2 | psxy ...
144 To extract all segments in the file big_file.d whose headers contain
146 the string "RIDGE AXIS", try
147 gmtconvert big_file.d -M -S"RIDGE AXIS" > subset.d
149
151 GMT(1), minmax(1)
152GMT 4.3.1 15 May 2008 GMTCONVERT(1)