I have list A:
['0.0720', '0.0200', '0.0260', '0.0210', '0.0740', '0.0510', '0.0160']
and also list B:
[
[0.074, 0.073, 0.072, 0.03, 0.029, 0.024, 0.021, 0.02],
[0.02, 0.015], [0.026, 0.02, 0.015],
[0.021, 0.02, 0.017],
[0.077, 0.076, 0.074, 0.055, 0.045, 0.021],
[0.053, 0.052, 0.051, 0.023, 0.022],
[0.016]
]
What is the most efficient method to compare the first element of A with the first sub-list of B, compare the first element of A with the second sub-list of B, compare the third element of A with the third sub-list of B, ..., and remove the corresponding element from the sub-list in B if they match and the sub-list contains 2 or more elements?
Using zip() you can pair up elements from two lists:
for a, b in zip(A, B):
# a is an element from A, b is a sublist from B.
Your sublists contain floating point values, and your list A contains strings. You'll need to figure out a tolerance for comparisons. Perhaps turning the floats to strings with the matching precision would suffice?
for a, b in zip(A, B):
# a is an element from A, b is a sublist from B.
b[:] = [i for i in b if format(i, '.4f') != a]
Using a slice assignment (b[:]) we replace the contents of the sublist with all elements that do not match a at 4 digits after the decimal.
Running that on your example input gives me:
[
[0.074, 0.073, 0.03, 0.029, 0.024, 0.021, 0.02],
[0.015],
[0.02, 0.015],
[0.02, 0.017],
[0.077, 0.076, 0.055, 0.045, 0.021],
[0.053, 0.052, 0.023, 0.022],
[]
]
If you only want the first match to be removed, use:
try:
del b[next(i for i, e in enumerate(b) if format(e, '.4f') == a)]
except StopIteration:
pass
This'll find the first index that matches, and remove that from b. Result (in this case exactly the same as before):
[[0.074, 0.073, 0.03, 0.029, 0.024, 0.021, 0.02],
[0.015],
[0.02, 0.015],
[0.02, 0.017],
[0.077, 0.076, 0.055, 0.045, 0.021],
[0.053, 0.052, 0.023, 0.022],
[]]