I would like to replace elements of a list b for elements from another list a
#my list is
b = [('ba'),
('bb'),
('bc'),
('bd'),
('be'),
('bf'),
('bg'),
('bh'),
('bi')]
#The second list
a = [('bc_1'),
('bd_1'),
('be_1'),
('bf_1'),
('bg_1')]
I would like to replace 'bc', 'bd', 'be', 'bf', 'bg' with 'bc_1', 'bd_1', 'be_1', 'bf_1', 'bg_1'
I tried with the next code
for i in a:
if i in b:
a = a.str.replace(i)
but it does not work
IIUC you want to replace the values in a if the part before the _ matches.
An efficient solution to avoid constantly looping over the values of a is to first build a dictionary to perform the match.
Then use a simple list comprehension.
a2 = {e.split('_')[0]: e for e in a}
output = [a2.get(e, e) for e in b]
output: ['ba', 'bb', 'bc_1', 'bd_1', 'be_1', 'bf_1', 'bg_1', 'bh', 'bi']
This solution will be much faster, especially on large datasets, as the indexing in dictionaries is O(1) due to the hashing of the keys.
content of a2:
{'bc': 'bc_1', 'bd': 'bd_1', 'be': 'be_1', 'bf': 'bf_1', 'bg': 'bg_1'}
Try this:
output = []
for j in b:
for i in a:
if i.startswith(f"{j}_"):
output.append(i)
break
else:
output.append(j)
then
>>> output
['ba', 'bb', 'bc_1', 'bd_1', 'be_1', 'bf_1', 'bg_1', 'bh', 'bi']
Compare two letters of b and two letter of a to see if they are the same
for index, a_value in enumerate(b):
for b_value in a:
if a_value[0] == b_value[0] and a_value[1] == b_value[1]:
b_value[index] = a_value
output :
b = ['ba', 'bb', 'bc_1', 'bd_1', 'be_1', 'bf_1', 'bg_1', 'bh', 'bi']
for index, b_value in enumerate(b):
length = len(b_value)
for a_value in a:
count = 0
for k in range(length):
if b_value[k] == a_value[k]:
count += 1
else:
break
if count == length:
b[index] = a_value
for i in range(len(b)):
for j in range(len(a)):
if b[i] in a[j]:
b[i]=a[j]
This should do the job for you. Currently your elements in the list are integers. But if your elements in the list are tuple then this wont work because tuple does not support item assignment. You will have to convert b and a to list of lists like so a = [['bc_1'],['bd_1']] etc. Then the below code will work.
for i in range(len(b)):
for j in range(len(a)):
if b[i][0] in a[j][0]:
b[i][0]=a[j][0]
b[i] in a[j] will match too broadly. For example 'b' in 'abc' is also True.