WANtaroHP (GMT: Simple use)

Outline of this page

Following items are shown in this page.

Frame for Semi-Log graph and Log-Log graph

GMT command	GMT command

Plot on Semi-Log praph

GMT command

Use of 2-axes

GMT command

Error bar

GMT command	GMT command

Plot size and plot color

GMT command	GMT command	GMT command

Polar coordinates

GMT command	GMT command
Range of r is from 0 to 100.	Range of r is from 0 to 10.
Grid interval in r-direction is 20.	Grid interval in r-direction is 1.

It is necessary to note that thr grid in radius-direction is not drawn at the area of radius being less than 5.

Draw sectors (use of -Sw or -SW for psxy)

The explanations for -Sw and -SW option to draw sectors (pie wedge plots) for psxy in the 'GMT manpages' are shown below:

• -Sw pie wedge. Start and stop directions (in degrees counter-clockwise from horizontal) for pie slice must be found in columns 3 and 4.
• -SW Same as -Sw, except azimuths (in degrees east of north) should be given instead of the two directions. The azimuths will be mapped into angles based on the chosen map projection (-Sw leaves the directions unchanged.)

Although Manpage say that start and stop directions must be found in colomns 3 and 4, start and stop directions shall be put in columns 4 and 5. Because center coordinates and radius of the sector shall be defined before start and stop directions. Actual inputted data row is shown below:

x y Radius StartAngle EndAngle

x , y and Radius mean the center coordinates and radius of the sector. StartAngle and EndAngle mean the start and end directions in degrees.

Sample drawings using -SW option for psxy are shown below.

GMT command

This article was written using information by following site.

http://xenocoder.wordpress.com/2008/08/01/creating-pie-wedge-plots-in-gmt/

I say thank you for the webmaster of above site.

Use of minmax

GMT has the function of minmax. This function can search number of data, minimum value and maximum value of each coloum in data set. A sample use of minmax is shown below including some awk scripts.

Input data

0.1
0.2
0.3
0.4
0.5

1 10
2 20
3 30
4 40
5 50

1 10 100 1000 10000
2 20 200 2000 20000
3 30 300 3000 30000
4 40 400 4000 40000
5 50 500 5000 50000

Batch file

rem Use of minmax
minmax test1.txt > _temp0.txt
minmax test2.txt >> _temp0.txt
minmax test3.txt >> _temp0.txt

rem Temporary treatment
gawk "NR==1{str0=$0;sub(/(: N =)/,\"\",str0);gsub(/</,\"\",str0);gsub(/>/,\"\",str0);print str0}" _temp0.txt > _temp1.txt
gawk "NR==2{str0=$0;sub(/(: N =)/,\"\",str0);gsub(/</,\"\",str0);gsub(/>/,\"\",str0);print str0}" _temp0.txt >> _temp1.txt
gawk "NR==3{str0=$0;sub(/(: N =)/,\"\",str0);gsub(/</,\"\",str0);gsub(/>/,\"\",str0);print str0}" _temp0.txt >> _temp1.txt

rem Get number of data, min.value and max.value
gawk "NR==1{nd=$2;split($3,a,\"/\");print nd,a[1],a[2]}" _temp1.txt > _temp2.txt
gawk "NR==2{nd=$2;split($4,a,\"/\");print nd,a[1],a[2]}" _temp1.txt >> _temp2.txt
gawk "NR==3{nd=$2;split($7,a,\"/\");print nd,a[1],a[2]}" _temp1.txt >> _temp2.txt

Output

Ooutput by minmax of GMT

test1.txt: N = 5 <0.1/0.5>
test2.txt: N = 5 <1/5> <10/50>
test3.txt: N = 5 <1/5> <10/50> <100/500> <1000/5000> <10000/50000>

note) 'tab' is changed to blank (space) in above file '_temp0.txt'

Ooutput by temporary treatment

test1.txt 5 0.1/0.5
test2.txt 5 1/5 10/50
test3.txt 5 1/5 10/50 100/500 1000/5000 10000/50000

note) 'tab' is changed to blank (space) in above files '_temp1.txt'

Number of data, minimum value and maximum value for specified column

5 0.1 0.5      | for column 1 of file 'test1.txt'
5 10 50        | for column 2 of file 'test2.txt'
5 10000 50000  | for column 5 of file 'test3.txt'