title: Replace blank spaces of a list
body: <p>My script gives 2 string lists, <code>a</code> and <code>b</code> . I want to convert them to float lists to do some calculations, but the lists have some gaps. For example, i have  <code>a = ["1"," ","3","4"]</code> and i want to fill those gaps with 0 and have this <code>a = ["1","0","3","4"]</code></p>