How can I iterate through a 2D list to just get the first index within each list?

user_17670129 0
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groups = [["Jobs", "Gates"], ["Newton", "Euclid"], ["Einstein", "Feynman"]]
 
# This outer loop will iterate over each list in the groups list
for group in groups:
  # This inner loop will go through each name in each list
  for name in group:
    print(name)`

Print out 'Jobs', 'Newton', 'Einstein'

nested-for-loop for-loop list python
2 Answers

This is where list comprehensions are really nice in Python:

groups = [["Jobs", "Gates"], ["Newton", "Euclid"], ["Einstein", "Feynman"]]

print([group[0] for group in groups])

Result:

['Jobs', 'Newton', 'Einstein']

If you just want to do something with each individual first entry, you of course just do this:

for group in groups:
    print(group[0])

Or, without the indexing:

for (name, *__) in groups:
    print(name)
user_43901600

You can use list comprehension like this:

groups = [["Jobs", "Gates"], ["Newton", "Euclid"], ["Einstein", "Feynman"]]
groups_only_first = [x[0] for x in groups]
print(groups_only_first)
user_175561720
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