Question

I installed rdiff-backup on my arch linux box only to end up with the attribute error:

AttributeError: 'module' object has no attribute 'reduce'

The error exists in one of rdiff_backup classes, but I can not spot the error. The function reduce should be builtin, and I can not get the code to find the function.

The code from rdiff looks like this:

    def get_total_dest_size_change(self):
        """Return total destination size change

        This represents the total change in the size of the
        rdiff-backup destination directory.

        """
        addvals = [self.NewFileSize, self.ChangedSourceSize,
                           self.IncrementFileSize]
        subtractvals = [self.DeletedFileSize, self.ChangedMirrorSize]
        for val in addvals + subtractvals:
                if val is None:
                        result = None
                        break
        else:
                def addlist(l): return reduce(lambda x,y: x+y, l)
                result = addlist(addvals) - addlist(subtractvals)
        self.TotalDestinationSizeChange = result
        return result

And the error occurs in the locally defined addlist function.
I’ve tried to import the builtin module in the top of the file (statistics.py), both like

import __builtin__

and

from __builtin__ import reduce

and tried to change the namespace of the method like so:

def addlist(l): return __builtin__.reduce(lambda x,y: x+y, l)

But alas. Still the same error.

I’ve not been able to find any good information or solution so far, so maybe someone with a little tighter knowledge about python could take stab at it.

Thanks
m

Answer 1

reduce(lambda x,y: x+y, l) is an equivalent of sum(l). Can you try whether sum(l) works? Also, which python version are you using (sum is available in version >= 2.3)