BUG: not correct work str.split

[ilgrad]

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the master branch of pandas.

Reproducible Example

import pandas as pd

df = pd.DataFrame(columns=['url'])
df['url'] = ['https://qweqwe.com/2021-09-14/qweqwejpgqweqwe.jpg']
df['id'] = df['url'].str.split('/').str[-2].astype(str) + '_' + df['url'].str.split('/').str[-1].str.split('.jpg').str[0]
print(df['id'].iloc[0])

Issue Description

output: 2021-09-14_qweqw
true output: 2021-09-14_qweqwejpgqweqwe

Expected Behavior

2021-09-14_qweqwejpgqweqwe

Installed Versions

python 3.9
pandas version 1.3.2

[debnathshoham]

I can confirm this on master, and I think should work given it works on str.split.

In [23]: 'qweqwejpgqweqwe.jpg'.split(".jpg")[0]
Out[23]: 'qweqwejpgqweqwe'

For your case, you can add an escape character and it should work (.jpg -> \.jpg).

In [1]: import pandas as pd
   ...: 
   ...: df = pd.DataFrame(columns=['url'])
   ...: df['url'] = ['https://qweqwe.com/2021-09-14/qweqwejpgqweqwe.jpg']
   ...: df['id'] = df['url'].str.split('/').str[-2].astype(str) + '_' + df['url'].str.split('/').str[-1].str.split('\.jpg').str[0]
   ...: print(df['id'].iloc[0])
   ...: 
2021-09-14_qweqwejpgqweqwe

[asishm]

maybe the documentation could be improved here, but with .str.split uses regex where len(pat) > 1

OR an enhancement to include a regex=True parameter as it exists for str.replace

pandas/pandas/core/strings/object_array.py

Lines 311 to 326 in 0a9f9ee

	def _str_split(self, pat=None, n=-1, expand=False):
	if pat is None:
	if n is None or n == 0:
	n = -1
	f = lambda x: x.split(pat, n)
	else:
	if len(pat) == 1:
	if n is None or n == 0:
	n = -1
	f = lambda x: x.split(pat, n)
	else:
	if n is None or n == -1:
	n = 0
	regex = re.compile(pat)
	f = lambda x: regex.split(x, maxsplit=n)
	return self._str_map(f, dtype=object)

[asishm]

also see related : #37963

[mzeitlin11]

I like the idea of adding a regex arg since that would be consistent with replace. It feels arbitrary to choose whether or not to treat as a regex based on being a single character or not

[saehuihwang]

take