# Removing elements of a list: remove

### 5.40.9 Removing elements of a list: remove

The remove command removes elements of a list according to a given conditions.

- remove takes two arguments:
  - f, a boolean function.
  - L, a list.
- remove(f,L) returns the sublist of L with the elements c such that f(c)==true removed.

#### Example.

Input:

remove(x->(x>=2),[0,1,2,3,1,5])

Output:

⎡ ⎣ | 0,1,1 | ⎤ ⎦

Remark: You can use remove to remove characters from a string. For example, to remove all the "a"s of a string (see Section 12.1.2 for writing functions):
Input:

orda := ord("a"):;

then:

`f(chn):={`
`local l:=length(chn)-1;`
`return remove(x->(ord(x)==orda),seq(chn[k],k,0,l));`
`}`

Now:
Input:

f("abracadabra")

Output:

⎡ ⎣ | "b","r","c","d","b","r" | ⎤ ⎦

To get a string:
Input:

char(ord(["b","r","c","d","b","r"]))

Output:

"brcdbr"