CODEWITHSUNDEEP
pythonstringintegerdigits
George Burrows
George Burrows

Reputation: 3501

How to manipulate digits within an integer/string?

I am looking for a general way to refer to particular digits in a integer or string, I need to be able to perform different operations on alternating digits and sum the result of all of those returned values.

Any help is much appreciated

Oh and I am a complete beginner so idiot-proof answers would be appreciated.

I will elaborate, is there any inbuilt function on Python that could reduce an integer into a list of it's digits, I have looked to no avail and I was hoping someone here would understand what I was asking, sorry to be so vague but I do not know enough of Python yet to provide a very in-depth question.

Upvotes: 2

Views: 33976

Answers (3)

AlG
AlG

Reputation: 15167

I'm not going to claim this is the best answer, but it meets your requirements:

In [1]: x = 1003998484

In [2]: [int(y) for y in str(x)]
Out[2]: [1, 0, 0, 3, 9, 9, 8, 4, 8, 4]

Or, if your input is already a string you can omit the str() cast:

In [1]: x = '482898477382'

In [2]: [int(y) for y in x]
Out[2]: [4, 8, 2, 8, 9, 8, 4, 7, 7, 3, 8, 2]

From there you can modify the resulting list as needed...

Upvotes: 0

retracile
retracile

Reputation: 12349

To just convert a string to a list of digits:

digits = [int(x) for x in mystr]

Lists are mutable, so you can modify individual digits this way.

Converting back to a string (assuming all your numbers are single-digit values):

''.join([str(x) for x in digits])

And you can use strides in slicing to deal with alternating digits

digits[::2]
digits[1::2]

Upvotes: 0

Russell Borogove
Russell Borogove

Reputation: 19057

If you're starting with an integer, first convert it to a string; you can't address the digits within an integer conveniently:

>>> myint = 979
>>> mystr = str(myint)
>>> mystr
'979'

Address individual digits with their index in square brackets, starting from zero:

>>> mystr[1]
'7'

Convert those digits back to integers if you need to do math on them:

>>> int(mystr[1])
7

And if you're just doing a numerological summation, list comprehensions are convenient:

>>> sum( [ int(x) for x in mystr ] )
25

Just keep in mind that when you're considering individual digits, you're working with strings, and when you're doing arithmetic, you're working with integers, so this kind of thing requires a lot of conversion back and forth.

Upvotes: 4

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