{expr1} must be a |List| or a |Dictionary|. For each item in {expr1} evaluate {expr2} and when the result is zero remove the item from the |List| or |Dictionary|. {expr2} must be a |string| or |Funcref|. If {expr2} is a |string|, inside {expr2} |v:val| has the value of the current item. For a |Dictionary| |v:key| has the key of the current item and for a |List| |v:key| has the index of the current item. Examples: call filter(mylist, 'v:val !~ "OLD"') Removes the items where "OLD" appears. call filter(mydict, 'v:key >= 8') Removes the items with a key below 8. call filter(var, 0) Removes all the items, thus clears the |List| or |Dictionary|. Note that {expr2} is the result of expression and is then used as an expression again. Often it is good to use a |literal-string| to avoid having to double backslashes. If {expr2} is a |Funcref| it must take two arguments: 1. the key or the index of the current item. 2. the value of the current item. The function must return |TRUE| if the item should be kept. Example that keeps the odd items of a list: func Odd(idx, val) return a:idx % 2 == 1 endfunc call filter(mylist, function('Odd')) It is shorter when using a |lambda|: call filter(myList, {idx, val -> idx * val <= 42}) If you do not use "val" you can leave it out: call filter(myList, {idx -> idx % 2 == 1}) The operation is done in-place. If you want a |List| or |Dictionary| to remain unmodified make a copy first: :let l = filter(copy(mylist), 'v:val =~ "KEEP"') Returns {expr1}, the |List| or |Dictionary| that was filtered. When an error is encountered while evaluating {expr2} no further items in {expr1} are processed. When {expr2} is a Funcref errors inside a function are ignored, unless it was defined with the "abort" flag. Can also be used as a |method|: mylist->filter(expr2)