Parse a string of floats in Python

Question

list=[['10, 0.01, 0.0428, 120; 30, 0.1, 2, 33; 50, 0.023, 0.31, 0.65'],
      ['10, 0.7, 0.5428, 2.31'],
      ['50, 0.3, 0.35, 0.1'],
      ['-10, 0.2, 0.048, 124; -30, 0.11, 24, 3; -50, 0.02, 0.1, 0.60; 0, 0, 0, 0; 10, 0.1, 2, 33; 
       20, 0.023, 0.31, 0.66']]

df=pd.DataFrame(list)

I have a dataframe df from which I am trying to get the 3rd value after each semicolon sign if the column name matches with the 1st value after the semicolon sign. The expected output is as below. Any clue on how to tackle this in a simple way?

How did you get this list? Yes you can parse the floats, but you probably want to fix the source — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Oct 4, 2021 at 19:45
@juanpa.arrivillaga the actual data is a dataframe of 1000s of rows saved locally on my system, i have replicated a few rows in a list so people can copy and try on their system — newman
– newman, Commented Oct 4, 2021 at 19:48

Corralien · Accepted Answer · 2021-10-06 07:18:42Z

1

Use nested loops:

d = {}
for r, i in enumerate(l):
    for j in i[0].split(';'):
        k = j.split(',')
        c, v = int(k[0]), float(k[2])
        d[(r, c)] = v

df = pd.Series(d).unstack(fill_value=0)

Output:

>>> df
   -50   -30    -10   0       10    20   30    50
0  0.0   0.0  0.000  0.0  0.0428  0.00  2.0  0.31
1  0.0   0.0  0.000  0.0  0.5428  0.00  0.0  0.00
2  0.0   0.0  0.000  0.0  0.0000  0.00  0.0  0.35
3  0.1  24.0  0.048  0.0  2.0000  0.31  0.0  0.00

edited Oct 6, 2021 at 7:18

answered Oct 4, 2021 at 21:21

Corralien

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6 Comments

ddejohn Over a year ago

OP wants the third item, which is k[2]!

Corralien Over a year ago

@ddejohn You really pay more attention than me :) Thanks.

Corralien Over a year ago

@RahulKumar. I updated my answer. Can you check it please?

ddejohn Over a year ago

You always answer a hair faster than me lol, it's the least I can do to get back at you for beating me to the punch.

Corralien Over a year ago

@ddejohn. I will not do it again, I promise :)

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