Splitting strings within nested lists in Python and converting to float?

Question

I am trying to split my nested list of strings into nested lists of floats. My nested list is below:

nested = [['0.3, 0.4, 0.2', '0.5, 0.1, 0.3'], ['0.7, 0.4, 0.2'], ['0.4, 0.1, 0.3']]

My desired output would be a nested list where these values remain in their sublist and are converted to floats as seen below:

nested = [[0.3, 0.4, 0.2, 0.5, 0.1, 0.3], [0.7, 0.4, 0.2], [0.4, 0.1, 0.3]]

The difficulty has come when trying to handle sublists with multiple strings (I.e. the first element). I have found some examples such as here How do I split strings within nested lists in Python?, but this code only handles sublists with one string element and I'm unsure how to apply this to sublists with multiple strings.

I am trying to avoid hardcoding anything as this is part of a script for a larger dataset and the sublist length may vary.

If anyone has any ideas, I'd appreciate some help.

Steven Rumbalski · Accepted Answer · 2020-07-29 19:30:19Z

3

result = [[float(t) for s in sublist for t in s.split(', ')] for sublist in nested]

which is equivalent to

result = []
for sublist in nested:
    inner = []
    for s in sublist:
        for t in s.split(', '):
            inner.append(float(t))
    result.append(inner)

answered Jul 29, 2020 at 19:30

Steven Rumbalski

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Mark Bennett · Accepted Answer · 2020-07-29 19:26:00Z

0

OK, starting with your example:

myNestedList = [['0.3, 0.4, 0.2', '0.5, 0.1, 0.3'], ['0.7, 0.4, 0.2'], ['0.4, 0.1, 0.3']]

myOutputList = []
for subList in myNestedList:
    tempList = []
    for valueStr in sublist:
        valueFloat = float( valueStr )
        tempList.append( valueFloat )
    myOutputList.append( tempList )

It will look something like that. (don't have time to try it out, but pretty close to correct)

answered Jul 29, 2020 at 19:26

Mark Bennett

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Iuri Guilherme · Accepted Answer · 2020-07-29 20:41:16Z

0

nested = [['0.3, 0.4, 0.2', '0.5, 0.1, 0.3'], ['0.7, 0.4, 0.2'], ['0.4, 0.1, 0.3']]

new_nested = [[float(number) for strings in sublist for number in strings.split(', ')] for sublist in nested]

print(new_nested)

new_nested = list()

for sublist in nested:
  sublist_new_nested = list()
  for strings in sublist:
    for number in strings.split(', '):
      sublist_new_nested.append(float(number))
  new_nested.append(sublist_new_nested)

print(new_nested)

Output:

[[0.3, 0.4, 0.2, 0.5, 0.1, 0.3], [0.7, 0.4, 0.2], [0.4, 0.1, 0.3]]
[[0.3, 0.4, 0.2, 0.5, 0.1, 0.3], [0.7, 0.4, 0.2], [0.4, 0.1, 0.3]]

edited Jul 29, 2020 at 20:41

answered Jul 29, 2020 at 19:43

Iuri Guilherme

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