CODEWITHSUNDEEP
pythonlistpython-3.x
tau woobunker
tau woobunker

Reputation: 151

How to print multiple non-consecutive values from a list with Python 3.5.1

I have created a list and want to choose a handful of items to print from the list. Below, I'd just like to print out "bear" at index 0 and "kangaroo" at index 3. My syntax is not correct:

>>> animals = ['bear', 'python', 'peacock', 'kangaroo', 'whale', 'platypus']
>>> print (animals[0,3])

Traceback (most recent call last): File "", line 1, in print (animals[0,3]) TypeError: list indices must be integers or slices, not tuple

I tried with a space between the indexes but it still gives an error:

>>> print (animals[0, 3])

Traceback (most recent call last): File "", line 1, in print (animals[0, 3]) TypeError: list indices must be integers or slices, not tuple

I am able to print a single value or a range from 0-3, for example, with:

>>> print (animals [1:4])
['python', 'peacock', 'kangaroo']

How can I print multiple non-consecutive list elements?

Upvotes: 13

Views: 45441

Answers (5)

Adam
Adam

Reputation: 1

print(animals[0] + " " + animals[3] + " " + ...)

Upvotes: 0

Will
Will

Reputation: 200

Python's list type does not support that by default. Return a slice object representing the set of indices specified by range(start, stop, step).

class slice(start, stop[, step])

>>>animals[0:5:2]
['bear', 'peacock', 'whale']

Either creating a subclass to implement by yourself or getting specified values indirectly. e.g.:

>>>map(animals.__getitem__, [0,3])
['bear', 'kangaroo']

Upvotes: 2

Mad Physicist
Mad Physicist

Reputation: 114320

list(animals[x] for x in (0,3)) is the subset you want. Unlike numpy arrays, native Python lists do not accept lists as indices.

You need to wrap the generator expression in list to print it because it does not have an acceptable __str__ or __repr__ on its own. You could also use str.join for an acceptable effect: ', '.join(animals[x] for x in (0,3)).

Upvotes: 7

Ashwini Chaudhary
Ashwini Chaudhary

Reputation: 250961

To pick arbitrary items from a list you can use operator.itemgetter:

>>> from operator import itemgetter    
>>> print(*itemgetter(0, 3)(animals))
bear kangaroo
>>> print(*itemgetter(0, 5, 3)(animals))
bear platypus kangaroo

Upvotes: 10

TigerhawkT3
TigerhawkT3

Reputation: 49318

Slicing with a tuple as in animals[0,3] is not supported for Python's list type. If you want certain arbitrary values, you will have to index them separately.

print(animals[0], animals[3])

Upvotes: 9

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