CODEWITHSUNDEEP
pythonstringunicode
Kumi
Kumi

Reputation: 1

String operations not working on python strings

I am using xlrd to read xls cell into a string, after which none of the string functions work on that string.

attribute_name = str(worksheet.cell_value(row,col))
attribute_name.strip()
attribute_name.lower()
print len(attribute_name)
if(len(attribute_name) > 8):
    print 'value' + str(ord(attribute_name[8]))
    print 'attributename:'+attribute_name+':'

prints : 

9
value32
attributename:TSA01_HE :
9
value32
attributename:TSA02_HE :

I am mainly interested in getting rid of the whitespace at the end of the attribute name. Am I missing anything obvious ? I have tried replace etc but as you can see, even .lower() doesnt work.

$ python --version Python 2.7.5

Upvotes: 0

Views: 66

Answers (3)

Joël
Joël

Reputation: 2822

Take care that both strip() and lower() do not modify the string you apply them on; you should therefore do attribute_name = attribute_name.strip().lower().

Example:

>>> a = '   A   '
>>> a.strip().lower()
'a'
>>> a
'   A   '

Upvotes: 0

zhangxaochen
zhangxaochen

Reputation: 34027

Methods like str.XXX always return new strings instead of edit the original string. This is because strings are immutables in python. Likewise, operators on string like += rebinds the variable to a new string as well:

In [755]: s='a'

In [756]: id(s)
Out[756]: 30887376

In [757]: s+='bc' #same as s=s+'bc'

In [758]: id(s) #identity of the variable has been changed
Out[758]: 301145192

So if you wish your operation on a string to take effect, always remember to assign the result back with =.

Other immutables like ints, floats, tuples, frozensets works the same as strs. E.g., you won't expect i=3; i.__add__(10) makes i==13.

Upvotes: 2

Jayanth Koushik
Jayanth Koushik

Reputation: 9904

strip and lower do not work in place; they return the changed value. So you should assign their result to the old variable.

attribute_name = attribute_name.strip().lower()

Upvotes: 2

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