Why str.lstrip will truncate letter e for words beginning with e but not for other letters?

Question

Strangely I met with this problem when I was trying to take out contents from an excel file with Python using xlrd modulus.

The example is like below:

Python 2.7.6 (default, Mar 22 2014, 22:59:38) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a="text:u'ethos'"
>>> a
"text:u'ethos'"
>>> a.lstrip("text:u'").rstrip("'")
'hos'
>>> b="text:u'weekend'"
>>> b
"text:u'weekend'"
>>> b.lstrip("text:u'").rstrip("'")
'weekend'

a cell reading out from xlrd is in text:u'' format for I need to get only the word.

ALthough I finally use table.cell_value() method to solve it. But I wonder why?

So why 'weekend' is working well but for word like 'ethos' is wrong?

If you have a fixed set of start and end characters, consider an explicit slice: `"text:u'weekend'"[7:-1]` — jonrsharpe, Dec 17 '14 at 14:08
@jonrsharpe Wonderful Solution! I did not realize that! Yeah it is fixed set of starting characters. — sikisis, Dec 17 '14 at 14:13
@AshwiniChaudhary Thank you! I understand why! Thank you! I hastily only read the tutorials rather than read the documents . — sikisis, Dec 17 '14 at 14:13

score 2 · Accepted Answer · answered Dec 17 '14 at 14:02

2

You should take a closer look at the lstrip function https://docs.python.org/2/library/stdtypes.html#str.lstrip

Return a copy of the string with leading characters removed. The chars argument is a string specifying the set of characters to be removed. If omitted or None, the chars argument defaults to removing whitespace. The chars argument is not a prefix; rather, all combinations of its values are stripped:

It ends up stripping out the characters t, e, x, :, and u until it reaches a different character. For "text:u'ethos'", every character up to 'h' is in that list, so it removes them. With "text:w'weekend'", since 'w' is not in that list it stops stripping characters there.

answered Dec 17 '14 at 14:02

David Reeve

863
9
16

so it is far better to use some including methods like table.cell_value() than write lstrip method myself? – sikisis Dec 17 '14 at 14:09
Or using Regular Expression is far more better than something like lstrip("text:u'")? – sikisis Dec 17 '14 at 14:10
I would use regex myself. – David Reeve Dec 17 '14 at 14:17

Why str.lstrip will truncate letter e for words beginning with e but not for other letters?

1 Answers1