On 12/08/2011 05:03 PM, Steven D'Aprano wrote:
Robert Berman wrote:
Hi,
Assuming a list similar to this: l1=[['a',1],['b',2],['c',3]] and I
want to get the index of 'c'.
You will need to explain what you mean by "the index of 'c'".
Do you mean 0, because 'c' is in position 0 of the sub-list ['c', 3]?
Or do you mean 2, because 'c' is in the sub-list at position 2?
What happens if there is a sub-list ['d', 'c']? Should that also
count? What about sub-sub-lists, should they be checked too?
Here is a version which checks each sub-list in turn, and returns the
index of any 'c' it finds of the first such sub-list.
def inner_find(list_of_lists):
for sublist in list_of_lists:
try:
return sublist.index('c')
except ValueError:
pass # go to the next one
# If not found at all:
raise ValueError('not found')
Here's a version which finds the index of the first sub-list that
begins with 'c' as the zeroth element:
def match_sublist(list_of_lists):
for i, sublist in enumerate(list_of_lists):
if sublist and sublist[0] == 'c':
return i
raise ValueError('not found')
Other variations on these two techniques are left for you to
experiment with.
Thank you Steven and Joel. You have given me information to experiment
with which is most appreciated.
Robert
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