Hi,
I have a list of lists. The number of sublists may vary. The sizes of
the sublists may also vary. For instance, here I have a list with 3
sublists of differing sizes.
[['a', 'b', 'c'], ['d', 'e'], ['f', 'g', 'h', 'i']]
This list will never be any deeper than this one level.
What I would like to do is flatten this list, rearrange the items in
the new flattened list and then recreate the list of sublists with the
new content. I would like the sublists to have the same size and order
(relative to each other) as before.
My code below seems to work, but it feels a bit "hack'ish", and I
am concerned about efficiency - so I would appreciate suggestions.
Again, the number of sublists may vary, and sizes of sublists are not
always the same (there will always be at least one sublist).
thanks!
Esmail
Here is my working code so far.
----------------
#!/usr/bin/env python
from random import shuffle
##################################################################
def flatten_list(parts):
""" flatten parts, and return index vals where to split """
line = sum(parts, []) # join all parts into one
idx_vals = []
idx = 0
for item in parts: # keep track of lengths/index values
idx += len(item)
idx_vals.append(idx)
return line, idx_vals
##################################################################
def rebuilt_lists(line, idx):
""" rebuild list of list """
new_list = [line[0:idx[0]]]
for i in xrange(len(idx)-1):
new_list.append(line[idx[i]:idx[i+1]])
return new_list
##################################################################
def main():
indi = [['a', 'b', 'c'], ['d', 'e'], ['f', 'g', 'h', 'i']]
print 'indi :', indi
# flatten list of list
new_indi, idx_vals = flatten_list(indi)
print 'new_indi:', new_indi
print 'lengths :', idx_vals
print
# manipulate list
print 'shuffling new_indi'
shuffle(new_indi)
print 'new_indi:', new_indi
print
# rebuild list of lists
new_list = rebuilt_lists(new_indi, idx_vals)
print 'new_list:', new_list
if __name__ == '__main__':
main()
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