CODEWITHSUNDEEP
pythonstring
k0da
k0da

Reputation: 3

Extract some letters from a string and add hyphen in Python

have files with date attached in last part of filename. Like this.

string = 'blablablabla_20210812.jpg'

I extract that data like this.

string[-12:][:-4]

I want to add '-' between year, month and date. This is how I do.

string[-12:][:-4][:4] + '-' + string[-12:][:-4][4:][:2] + '-' + string[-12:][:-4][6:]

In my opinion, it seems like more complicated than reading machine code. Could you guys could enlighten me the ways which are more pragmatic?

Upvotes: 0

Views: 109

Answers (6)

Ahmar Shoeb
Ahmar Shoeb

Reputation: 89

You can also try like this:

import datetime 
print(datetime.datetime.strptime(string[-12:-4],'%Y%m%d').strftime('%Y-%m-%d'))

Output:

'2021-08-12'

Upvotes: 0

greghvk
greghvk

Reputation: 86

You can put both indices in one square and use join function:

'-'.join([string[-12:-8], string[-8:-6], string[-6:-4]])

Also, I personally prefer to keep code readable. You can name the variables first:

def extractDataInfo(string):
  year, month, day = string[-12:-8], string[-8:-6], string[-6:-4]
  return '-'.join([year, month, day])

Upvotes: 0

Eladtopaz
Eladtopaz

Reputation: 1054

A simple solution for this question will work only if you know that the file always ends with:

_data.extension

If so, the solution will be:

string = 'blablablabla_20210812.jpg'
s = string.replace("_", ".")
s = s.split(".")
data = s[1]
s[1] = data[:4] + "-" + data[4:6] + "-" + data[6:]
print(s[1]) # OUTPUT: 2021-08-12

# Taking all together:
print(s[0] + "_" + s[1] + "." + s[2])  # OUTPUT: blablablabla_2021-08-12.jpg

Upvotes: 0

Sefan
Sefan

Reputation: 709

You can compress the string[-12:][:-4][:4] to string[-12:-8] to make it look cleaner. The code will look like this:

string = 'blablablabla_20210812.jpg'
print(string[-12:-8] + '-' + string[-8:-6]+ '-' + string[-6:-4])
# 2021-08-12

Or this if you want the text:

print(string[:-8] + '-' + string[-8:-6]+ '-' + string[-6:-4])
# blablablabla_2021-08-12

Upvotes: 0

ThePyGuy
ThePyGuy

Reputation: 18426

You can also replace the values joining the groups with lambda:

>>> import re
>>> string = 'blablablabla_20210812.jpg'
>>> re.sub('(\d{4})(\d{2})(\d{2})', lambda m: '-'.join(g for g in m.groups()), string)

#output: 'blablablabla_2021-08-12.jpg'

Upvotes: 2

Andrej Kesely
Andrej Kesely

Reputation: 195543

One solution is to use regular expression and re.sub:

import re

s = "blablablabla_20210812.jpg"

s = re.sub(r"_(\d{4})(\d{2})(\d{2})\.", r"_\1-\2-\3.", s)
print(s)

Prints:

blablablabla_2021-08-12.jpg

Upvotes: 4

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