Sorry if this is trivial I'm still learning but I have a list of dictionaries that looks as follow:
[{'1102': ['00576', '00577', '00578', '00579', '00580', '00581']},
{'1102': ['00582', '00583', '00584', '00585', '00586', '00587']},
{'1102': ['00588', '00589', '00590', '00591', '00592', '00593']},
{'1102': ['00594', '00595', '00596', '00597', '00598', '00599']},
{'1102': ['00600', '00601', '00602', '00603', '00604', '00605']}
...]
it contains ~89000 dictionaries. And I have a list containing 4473208 paths. example:
['/****/**/******_1102/00575***...**0CT.csv',
'/****/**/******_1102/00575***...**1CT.csv',
'/****/**/******_1102/00575***...**2CT.csv',
'/****/**/******_1102/00575***...**3CT.csv',
'/****/**/******_1102/00575***...**4CT.csv',
'/****/**/******_1102/00578***...**1CT.csv',
'/****/**/******_1102/00578***...**2CT.csv',
'/****/**/******_1102/00578***...**3CT.csv',
...]
and what I want to do is group each path that contains the grouped values in the dict in the folder containing the key together.
I tried using for loops like this:
grpd_cts = []
for elem in tqdm(dict_list):
temp1 = []
for file in ct_paths:
for key, val in elem.items():
if (file[16:20] == key) and (any(x in file[21:26] for x in val)):
temp1.append(file)
grpd_cts.append(temp1)
but this takes around 30hours. is there a way to make it more efficient? any itertools function or something?
Thanks a lot!
CodePudding user response:
ct_paths
is iterated repeatedly in your inner loop, and you're only interested in a little bit of it for testing purposes; pull that out and use it to index the rest of your data, as a dictionary.
What does make your problem complicated is that you're wanting to end up with the original list of filenames, so you need to construct a two-level dictionary where the values are lists of all originals grouped under those two keys.
ct_path_index = {}
for f in ct_paths:
ct_path_index.setdefault(f[16:20], {}).setdefault(f[21:26], []).append(f)
grpd_cts = []
for elem in tqdm(dict_list):
temp1 = []
for key, val in elem.items():
d2 = ct_path_index.get(key)
if d2:
for v in val:
v2 = d2.get(v)
if v2:
temp1 = v2
grpd_cts.append(temp1)
ct_path_index
looks like this, using your data:
{'1102': {'00575': ['/****/**/******_1102/00575***...**0CT.csv',
'/****/**/******_1102/00575***...**1CT.csv',
'/****/**/******_1102/00575***...**2CT.csv',
'/****/**/******_1102/00575***...**3CT.csv',
'/****/**/******_1102/00575***...**4CT.csv'],
'00578': ['/****/**/******_1102/00578***...**1CT.csv',
'/****/**/******_1102/00578***...**2CT.csv',
'/****/**/******_1102/00578***...**3CT.csv']}}
The use of setdefault
(which can be a little hard to understand the first time you see it) is important when building up collections of collections, and is very common in these kinds of cases: it makes sure that the sub-collections are created on demand and then re-used for a given key.
Now, you've only got two nested loops; the inner checks are done using dictionary lookups, which are close to O(1).
Other optimizations would include turning the lists in dict_list
into sets, which would be worthwhile if you made more than one pass through dict_list
.