Groovy regex match list from readlines()

Question

I am trying to read a text file and return all lines that do not begin with a #. In python I could easily use list comprehension list

with open('file.txt') as f:
     lines = [l.strip('\n') for l in f.readlines() if not re.search(r"^#", l)]

I would like to accomplish the same thing via Groovy. So far I have the below code, any help is greatly appreciated.

lines = new File("file.txt").readLines().findAll({x -> x ==~ /^#/ })

Does that not work? You might need to change the findAll closure to `{ x -> !x.startsWith( '#' ) }` — tim_yates, Jan 24 '13 at 23:47
tim_yates - `lines = new File(masterManifest).readLines().findAll({x -> !x.startsWith('#')})` works perfectly. Thanks — Chris Powell, Jan 25 '13 at 00:10

score 5 · Answer 1 · answered Jan 24 '13 at 23:55

In groovy, you generally have to use collect in place of list comprehensions. For example:

new File("file.txt").readLines().findAll({x -> x ==~ /^#/ }).
    collect { it.replaceAll('\n', '') }

Note that readLines() already strips off newlines, so in this case it's not necessary.

For searching, you can also use the grep() method:

new File('file.txt').readLines().grep(~/^#.*/)

1 Answers1