Groovy filter two dimensions array

Question

​def a = [[6, 4], [8, 6], [5, 3]]

a.findAll {
   it.findAll {
      it != 4 && it != 6 
   }
}​​

So I have this pseudo code written so I wouldn't need to write my complex code. So I want to remove all the 4's from the array but if I write only it != 4 then it doesn't remove it, if I write both of the numbers as I wrote now it != 4 && it != 6 then it removes it. Should I use it somehow differently? I want this array

def a = [[6, 4], [8, 6], [5, 3]]

To remove all number 4's from it for example.

Answer 1

Remove sublist with 4 inside

Use the in syntax to check inside the sublist. So your code can be rewritten as:

def a = [[6,4],[8,6],[5,3]] 
assert  [[8, 6], [5, 3]] == a.findAll { !(4 in it) }

Remove 4 from every sublist

def a = [[6,4],[8,6],[5,3]] 
// Modify list in place, to return a new list use collect
assert  [[6], [8, 6], [5, 3]] == a.each{ it.removeAll { it == 4 } }

Answer 2

Since you need to modify the collection you need to use collect instead of findAll:

def a =  [
    [6, 4],
    [8, 6],
    [5, 3],
  ]

assert a.collect { l -> l.findAll { it != 4 } } == [[6], [8, 6], [5, 3]]