The result list contains single spaces when splitting a string with re.split("( )+") – is there a better way?
Question:
I have the output of a command in tabular form. I’m parsing this output from a result file and storing it in a string. Each element in one row is separated by one or more whitespace characters, thus I’m using regular expressions to match 1 or more spaces and split it. However, a space is being inserted between every element:
>>> str1 = "a b c d" # spaces are irregular
>>> str1
'a b c d'
>>> str2 = re.split("( )+", str1)
>>> str2
['a', ' ', 'b', ' ', 'c', ' ', 'd'] # 1 space element between!
Is there a better way to do this?
After each split str2 is appended to a list.
Answers:
When you use re.split and the split pattern contains capturing groups, the groups are retained in the output. If you don’t want this, use a non-capturing group instead.
The str.split method will automatically remove all white space between items:
>>> str1 = "a b c d"
>>> str1.split()
['a', 'b', 'c', 'd']
Docs are here: http://docs.python.org/library/stdtypes.html#str.split
By using (,), you are capturing the group, if you simply remove them you will not have this problem.
>>> str1 = "a b c d"
>>> re.split(" +", str1)
['a', 'b', 'c', 'd']
However there is no need for regex, str.split without any delimiter specified will split this by whitespace for you. This would be the best way in this case.
>>> str1.split()
['a', 'b', 'c', 'd']
If you really wanted regex you can use this ('s' represents whitespace and it’s clearer):
>>> re.split("s+", str1)
['a', 'b', 'c', 'd']
or you can find all non-whitespace characters
>>> re.findall(r'S+',str1)
['a', 'b', 'c', 'd']
Its very simple actually. Try this:
str1="a b c d"
splitStr1 = str1.split()
print splitStr1
I have the output of a command in tabular form. I’m parsing this output from a result file and storing it in a string. Each element in one row is separated by one or more whitespace characters, thus I’m using regular expressions to match 1 or more spaces and split it. However, a space is being inserted between every element:
>>> str1 = "a b c d" # spaces are irregular
>>> str1
'a b c d'
>>> str2 = re.split("( )+", str1)
>>> str2
['a', ' ', 'b', ' ', 'c', ' ', 'd'] # 1 space element between!
Is there a better way to do this?
After each split str2 is appended to a list.
When you use re.split and the split pattern contains capturing groups, the groups are retained in the output. If you don’t want this, use a non-capturing group instead.
The str.split method will automatically remove all white space between items:
>>> str1 = "a b c d"
>>> str1.split()
['a', 'b', 'c', 'd']
Docs are here: http://docs.python.org/library/stdtypes.html#str.split
By using (,), you are capturing the group, if you simply remove them you will not have this problem.
>>> str1 = "a b c d"
>>> re.split(" +", str1)
['a', 'b', 'c', 'd']
However there is no need for regex, str.split without any delimiter specified will split this by whitespace for you. This would be the best way in this case.
>>> str1.split()
['a', 'b', 'c', 'd']
If you really wanted regex you can use this ('s' represents whitespace and it’s clearer):
>>> re.split("s+", str1)
['a', 'b', 'c', 'd']
or you can find all non-whitespace characters
>>> re.findall(r'S+',str1)
['a', 'b', 'c', 'd']
Its very simple actually. Try this:
str1="a b c d"
splitStr1 = str1.split()
print splitStr1