CODEWITHSUNDEEP
pythonstringdata-extraction
user4378959
user4378959

Reputation: 19

Extraction of Numbers from String

I am trying to extract numbers from a string. Without any fancy inports like regex and for or if statements.

Example 495 * 89

Output 495 89

Edit I have tried this:

num1 = int(''.join(filter(str.isdigit, num)))

It works, but doesn't space out the numbers

Upvotes: 1

Views: 132

Answers (3)

OneCricketeer
OneCricketeer

Reputation: 191701

You're close.

You don't want to int() a single value when there are multiple numbers in the string. The filter function is being applied over characters, since strings are iterable that way

Instead, you need to first split the string into its individual tokens, then filter whole numerical strings, then cast each element

s = "123 * 54"
digits = list(map(int, filter(str.isdigit, s.split())))

Keep in mind, this only handles non-negative integers

Upvotes: 1

JL Peyret
JL Peyret

Reputation: 12154

You can do this without much fancy stuff

s = "495   *  89"

#replace non-digits with spaces, goes into a list of characters
li = [c if c.isdigit() else " " for c in s ]

#join characters back into a string
s_digit_spaces = "".join(li)

#split will separate on space boundaries, multiple spaces count as one
nums = s_digit_spaces.split()

print(nums)

#one-liner:
print ("".join([c if c.isdigit() else " " for c in s ]).split())

output:

['495', '89']
['495', '89']

#and with non-digit number stuff
s = "495.1   *  -89"
print ("".join([c if (c.isdigit() or c in ('-',".")) else " " for c in s ]).split())

output:

['495.1', '-89']

Finally, this works too:

print ("".join([c if c in  "0123456789+-." else " " for c in s ]).split())

Upvotes: 1

Tim Biegeleisen
Tim Biegeleisen

Reputation: 520978

Actually, regex is a very simple and viable option here:

inp = "495   *  89"
nums = re.findall(r'\d+(?:\.\d+)?', inp)
print(nums)  # ['495', '89']

Assuming you always expect integers and you want to avoid regex, you could use a string split approach with a list comprehension:

inp = "495   *  89"
parts = inp.split()
nums = [x for x in parts if x.isdigit()]
print(nums)  # ['495', '89']

Upvotes: 2

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