Question

I have some Python code that pulls strings out of a text file:

[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854, ....]

Python code:

v = string[string.index('['):].split(',')
for elem in v:
    new_list.append(float(elem))

This gives an error:

ValueError: could not convert string to float: [2.974717463860223e-06

Why can’t [2.974717463860223e-06 be converted to a float?

Answer 1

You’ve still got the [ in front of your “float” which prevents parsing.

Why not use a proper module for that? For example:

>>> a = "[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]"
>>> import json
>>> b = json.loads(a)
>>> b
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]

or

>>> import ast
>>> b = ast.literal_eval(a)
>>> b
[2.467188005806714e-05, 0.18664554919828535, 0.5026880460053854]