Remove empty strings from list

Helvin helvinlui at gmail.com
Tue Sep 15 03:49:58 CEST 2009


Hi,

Sorry I did not want to bother the group, but I really do not
understand this seeming trivial problem.
I am reading from a textfile, where each line has 2 values, with
spaces before and between the values.
I would like to read in these values, but of course, I don't want the
whitespaces between them.
I have looked at documentation, and how strings and lists work, but I
cannot understand the behaviour of the following:
                        line = f.readline()
			line = line.lstrip() # take away whitespace at the beginning of the
readline.
			list = line.split(' ') # split the str line into a list

                        # the list has empty strings in it, so now,
remove these empty strings
			for item in list:
				if item is ' ':
					print 'discard these: ',item
					index = list.index(item)
					del list[index]         # remove this item from the list
				else:
					print 'keep this: ',item
The problem is, when my list is :  ['44', '', '', '', '', '',
'0.000000000\n']
The output is:
    len of list:  7
    keep this:  44
    discard these:
    discard these:
    discard these:
So finally the list is:   ['44', '', '', '0.000000000\n']
The code above removes all the empty strings in the middle, all except
two. My code seems to miss two of the empty strings.

Would you know why this is occuring?

Regards,
Helvin



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