Difference between revisions of "Convert points to lines"

From GRASS-Wiki
Jump to: navigation, search
(+Converting CSV points file into lines map)
(+cats)
Line 35: Line 35:
  
 
[[Category: FAQ]]
 
[[Category: FAQ]]
 +
[[Category: Vector]]

Revision as of 09:58, 29 December 2011

Q: Is there a way to construct a vector line(s) map connecting selected points?

A: There are two possibilities:

Converting points map into lines map

You can use v.in.lines for that. The input can be generated with v.out.ascii.

Spearfish example:

  v.out.ascii archsites fs=, where="cat=1 or cat= 3"
  593493,4914730,1
  589860,4922000,3
 
  # so:
  v.out.ascii archsites fs=, where="cat=1 or cat= 3" | cut -d',' -f1,2 | \
      v.in.lines in=- out=myline fs=,
  v.category in=myline out=line_with_cat option=add

Converting CSV points file into lines map

Suppose you have a CSV file "mypoints.csv" containing three point-pairs to be connected (start point coordinates, end point coordinates):

 east1,north1,east2,north2
 593493,4914730,589860,4922000
 590400,4922820,593549,4925500
 600375,4925235,606635,4920773

We can convert these three point pairs into three lines:

  cat mypoints.csv | grep -v "north1" | awk -F',' '{printf "%f,%f\n%f,%f\nNaN,NaN\n",$1, $2 ,$3 ,$4}' > mypoints_formatted.csv
  v.in.lines in=mypoints_formatted.csv out=mylines fs=,
  v.category in=mylines out=lines_with_cat option=add