[GRASS-user] How to convert from point to line ?

GRASS GRASS user
1

Dear all

I am a beginner user of grass gis.

I want to import a text file that included latitude, longitude,ID number and
recordig time, into grass as line data.

The format style is as follows:

id,x,y,time
1,857.8629761,-785.6849976,1
1,987.9949951,-682.4140015,2
1,964.4849854,-710.6849976,3
2,1689.578979,-1070.564941,4
2,1654.074951,-1061.333008,5
2,1618.218018,-1040.505981,6
3,2335.930908,-1180.246948,7
3,2336.694092,-1197.869019,8
3,2336.658936,-1218.124023,9
4,2512.673096,-1689.875977,10
4,2494.010986,-1710.625977,11
5,1826.724976,-1731.743042,12
5,1808.57605,-1726.490967,13
5,1793.598999,-1723.034058,14
.....
.....
.....
.....

Firstly I intended to use 'v in ascii' command.

However, this command imports a text data into points, I think.

I want to import this text file into grass as line data according to the ID
number.

May this question be solved in grass? If it is so, please teach a solution....

Yasuo shimada: Japan weather assocation.

2

SGW00412@nifty.com wrote:

Dear all

I am a beginner user of grass gis.

So am I. But as nobody else seems to have a better idea... here is what I would do:

a) reformat yourdata into GMT format (yourdata.gmt) with a small AWK script

$ awk -f reformat_to_gmt.awk yourdata > yourdata.gmt

b) import yourdata.gmt into GRASS via v.in.ogr

$ v.in.ogr -o yourdata.gmt out=yourdata

(This assumes that you already have a GRASS location with the same projection as the coordinates in your data file).

Below some more details.

Hope this helps, Hermann

$ cat yourdata
id,x,y,time
1,857.8629761,-785.6849976,1
1,987.9949951,-682.4140015,2
1,964.4849854,-710.6849976,3
2,1689.578979,-1070.564941,4
2,1654.074951,-1061.333008,5
2,1618.218018,-1040.505981,6
3,2335.930908,-1180.246948,7
3,2336.694092,-1197.869019,8
3,2336.658936,-1218.124023,9
4,2512.673096,-1689.875977,10
4,2494.010986,-1710.625977,11
5,1826.724976,-1731.743042,12
5,1808.57605,-1726.490967,13
5,1793.598999,-1723.034058,14

$ cat reformat_to_gmt.awk
BEGIN { FS = "," }

NR == 1 {
        print "# @VGMT2.0 @GLINESTRING"
        print "# @NID"
        print "# @Tinteger"
        print "# FEATURE_DATA"
        next
}

prev != $1 { print ">" ORS "# @D" $1 }

{ print $2,$3 ; prev = $1 }

$ cat yourdata.gmt
# @VGMT2.0 @GLINESTRING
# @NID
# @Tinteger
# FEATURE_DATA

# @D1
857.8629761 -785.6849976
987.9949951 -682.4140015
964.4849854 -710.6849976

# @D2
1689.578979 -1070.564941
1654.074951 -1061.333008
1618.218018 -1040.505981

# @D3
2335.930908 -1180.246948
2336.694092 -1197.869019
2336.658936 -1218.124023

# @D4
2512.673096 -1689.875977
2494.010986 -1710.625977

# @D5
1826.724976 -1731.743042
1808.57605 -1726.490967
1793.598999 -1723.034058

3

Dear Yasou

You can import any geometric element using v.in.ascii. Use

*format*=///standard/

and include in your a header with primitive code L (that is line).

You can see an example at the manual page

http://grass.itc.it/grass62/manuals/html62_user/v.in.ascii.html

best regards

Juan Carlos Torres

SGW00412@nifty.com escribió:

Dear all

I am a beginner user of grass gis.

I want to import a text file that included latitude, longitude,ID number and recordig time, into grass as line data.

The format style is as follows:

id,x,y,time
1,857.8629761,-785.6849976,1
1,987.9949951,-682.4140015,2
1,964.4849854,-710.6849976,3
2,1689.578979,-1070.564941,4
2,1654.074951,-1061.333008,5
2,1618.218018,-1040.505981,6
3,2335.930908,-1180.246948,7
3,2336.694092,-1197.869019,8
3,2336.658936,-1218.124023,9
4,2512.673096,-1689.875977,10
4,2494.010986,-1710.625977,11
5,1826.724976,-1731.743042,12
5,1808.57605,-1726.490967,13
5,1793.598999,-1723.034058,14
.....

Firstly I intended to use 'v in ascii' command.

However, this command imports a text data into points, I think.

I want to import this text file into grass as line data according to the ID number.

May this question be solved in grass? If it is so, please teach a solution....

Yasuo shimada: Japan weather assocation.
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user
  

4

If you search in the mailing list archives you'll find a script
I wrote for someone some months ago to do this. (that was for
animal tracks IIRC). Input format is always different, so it's
hard, but possible, to come up with an automatic solution.

as mentioned by others, the typical solution is to use v.in.ascii
format=standard. See also v.in.mapgen but that doesn't give
you the line numbers.

Hamish

SGW00412 wrote:

I am a beginner user of grass gis.

I want to import a text file that included latitude,
longitude,ID number and
recordig time, into grass as line data.

The format style is as follows:

id,x,y,time
1,857.8629761,-785.6849976,1
1,987.9949951,-682.4140015,2
1,964.4849854,-710.6849976,3
2,1689.578979,-1070.564941,4
2,1654.074951,-1061.333008,5
2,1618.218018,-1040.505981,6
3,2335.930908,-1180.246948,7
3,2336.694092,-1197.869019,8
3,2336.658936,-1218.124023,9
4,2512.673096,-1689.875977,10
4,2494.010986,-1710.625977,11
5,1826.724976,-1731.743042,12
5,1808.57605,-1726.490967,13
5,1793.598999,-1723.034058,14
.....
.....
.....
.....

Firstly I intended to use 'v in ascii' command.

However, this command imports a text data into points, I
think.

I want to import this text file into grass as line data
according to the ID
number.

May this question be solved in grass? If it is so, please
teach a solution....

Yasuo shimada: Japan weather assocation.
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user