Question

I have a file which looks like below.

1   1  0  #  1 
6   1  0  #  2 
8   1  0  #  3 
10  1  0  #  4 
12  1  0  #  6 

How can I add .0 to all numbers, except the numbers behind the #. I think this should not be too difficult to do with a regular expression, but my regex knowledge is too rusty..

Answer 1

If your numbers after the # don’t have spaces after them, you can use:

:g/\([0-9]\+\) /s//\1.0 /g

The use of () creates groups which you can refer to as \D in the replacement text, where D is the position of the group within the search string. This will give you:

1.0   1.0  0.0  #  1
6.0   1.0  0.0  #  2
8.0   1.0  0.0  #  3
10.0  1.0  0.0  #  4
12.0  1.0  0.0  #  6

If they do have spaces after them (which yours seem to have), you’ll get:

1.0   1.0  0.0  #  1.0
6.0   1.0  0.0  #  2.0
8.0   1.0  0.0  #  3.0
10.0  1.0  0.0  #  4.0
12.0  1.0  0.0  #  6.0

in which case you can then do:

:g/\.0\(  *\)$/s//\1/g

to fix it up.