CODEWITHSUNDEEP
pythonpython-2.7list-comprehension
user2242044
user2242044

Reputation: 9213

How to combine two lists

I can write the append line two ways. Neither produce the desired result. Is there a way to wrap this up in 1 line?

Option 1:

row.append(x[1] for x in emails if x[0] == row[1])

Yields:

[['project1', 'email1', <generator object <genexpr> at 0x0227D670>], ['project1', 'email2', <generator object <genexpr> at 0x022EB8A0>]]

Option 2:

row.append([x[1] for x in emails if x[0] == row[1]])

Yields:

[['project1', 'email1', ['[email protected]']], ['project1', 'email2', ['[email protected]']]]

Desired Result:

[['project1', 'email1', '[email protected]'], ['project1', 'email2', '[email protected]']]

Code:

emails = [['email1','[email protected]'],['email2','[email protected]']]

projects = [['project1', 'email1'], ['project1', 'email2']]

for row in projects:
    row.append(x[1] for x in emails if x[0] == row[1])
print projects

Upvotes: 2

Views: 77

Answers (2)

John1024
John1024

Reputation: 113844

In your existing code, replace this one line:

row.append(x[1] for x in emails if x[0] == row[1])

With:

row.extend(x[1] for x in emails if x[0] == row[1])

One-line solution

Alternatively, eliminating the loop and condensing the code all into one line:

>>> projects = [  row + [x[1] for x in emails if x[0] == row[1]] for row in projects ]
>>> print projects 
[['project1', 'email1', '[email protected]'], ['project1', 'email2', '[email protected]']]

Upvotes: 4

Padraic Cunningham
Padraic Cunningham

Reputation: 180411

emails = [['email1','[email protected]'],['email2','[email protected]']]

projects = [['project1', 'email1'], ['project1', 'email2']]
from itertools import chain


print([list(set((chain.from_iterable(ele)))) for ele in zip(emails,projects)])
[['email1', '[email protected]', 'project1'], ['email2', 'project1', '[email protected]']]

Or:

print([list(set(ele).union(projects[ind])) for ind, ele in enumerate(emails)])

Or:

print([projects[ind] + [ele for ele in sub if ele not in projects[ind]] for ind, sub in enumerate(emails)])

All the different versions will work for multiple items not just checking against a single element.

Upvotes: 1

Related Questions