Question

I’m trying to accomplish the following:

Iterate a list
    if an element (string) does not have a '$' at the first position
        apply a '$'  and append the new value to the array

I’m trying something like:

  symbols = ['aol', 'goog', ...]
  (symbols.append('$'+val) if '$' != val[0] for val in symbols)

But I’m getting a syntax error.
Any help is appreciated.

Answer 1

Iterate over a shallow copy of the list and check for $ using str.startswith():

In [81]: symbols = ['aol', 'goog','$foo','bar']

In [82]: for x in symbols[:]:
    if not x.startswith('$'):
        symbols.append('$'+x)
   ....:         

In [83]: symbols
Out[83]: ['aol', 'goog', '$foo', 'bar', '$aol', '$goog', '$bar']