Split string of numbers with no whitespaces in python

Question

I have a string of numbers with no whitespaces like this:

s = '12.2321.4310.85'

I know that the format for each number is F5.2 (I am reading the string from a FORTRAN code output)

I need to obtain the following list of numbers based on s:

[12.23,21.43,10.85]

How can I do this in python?

Thanks in advance for any help!

There is something very very wrong with whatever is giving this data to you. Fix that instead of writing hacks to deal with it. — cs95
– cs95, Commented Dec 13, 2019 at 19:26
@cs95 This is from a text file output from a model written in FORTRAN. I am reading the text file because I need to modify this string of numbers later. — sebway
– sebway, Commented Dec 13, 2019 at 19:32
Slice the string into chunks of 5 characters. Convert each chunk to float. — Prune
– Prune, Commented Dec 13, 2019 at 19:32
BTW, what you've listed is FORTRAN format specification F5.2, not 4.2. It's total field width at the front. — Prune
– Prune, Commented Dec 13, 2019 at 19:35

Prune · Accepted Answer · 2019-12-13 19:34:37Z

3

Slice the string into chunks of 5 characters. Convert each chunk to float.

>>> [float(s[i:i+5]) for i in range(0, len(s), 5)]
[12.23, 21.43, 10.85]

answered Dec 13, 2019 at 19:34

Prune

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3 Comments

aminrd Over a year ago

There might be numbers like 1234.56 and 78.99 in the dataset using format 4.2 and generate s = "1234.5678.99"

sebway Over a year ago

Thank you @Prune, this works for me since I know the number of characters from the FORTRAN format.

Prune Over a year ago

@aminrd I just clarified with OP that this is not the case. Strict FORTRAN does not overrun the output field as other languages do ... often to my annoyance in college days.

Celius Stingher · Accepted Answer · 2019-12-13 19:31:42Z

0

If you are really sure of the format, and that will always be handed in that way then using a step of 5 in your loop might work:

s = '12.2321.4310.85'
output = []
for i in range(0,len(s),5):
    output.append(float(s[i:i+5]))
print(output)

Output:

[12.23, 21.43, 10.85]

answered Dec 13, 2019 at 19:31

Celius Stingher

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4 Comments

aminrd Over a year ago

I'm not sure, but couldn't format 4.2 generate something like 1234.56 in python?

Celius Stingher Over a year ago

Yes, the size of 5 assumes there's 2 decimal places, 1 ones and 1 tens.

aminrd Over a year ago

My point is, there might be numbers like 1234.56 and 78.99 in the dataset using format 4.2 and generate s = "1234.5678.99"

Celius Stingher Over a year ago

Yes, that's why I specified the condition in my previous comment.

aminrd · Accepted Answer · 2019-12-13 19:45:09Z

0

I think the safest way is to rely on . points. Because we know that every floating point should have one fraction and always there are two fraction numbers (there might be values like 1234.56 and 78.99 in the data that generates s = "1234.5678.99"). But we are not sure how many digits are before .. So we can extract values one by one based on ..

s = '12.2321.4310.85'
def extractFloat(s):
    # Extracts the first floating number with 2 floatings from the string
    return float( s[:s.find('.')+3]) , s[s.find('.')+3:]

l = []
while len(s) > 0:
    value, s = extractFloat(s)
    l.append(value)

print(l)
# Output: 
# [12.23, 21.43, 10.85]

answered Dec 13, 2019 at 19:45

aminrd

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