list1 = []
list.append([item1[i], item2[i], item3[i] for i in range(2)])
i.e how to populate list1 with [[item1[0], item2[0], item3[0]],[item1[1], item2[1], item3[1]]] through list comprehension where item1, item2 item3 are different lists?
Example:
item1 = [1,2,3,4]
item2 = [1,4,9,16]
item3 = [1,8,27,64]
# I want list1 =
[[1,1,1],
[2,4,8],
[3,9,27],
[4,16,64]]
# through list comprehension AND APPEND STATEMENT
Try this:
list1 = list(zip(item1, item2, item3))
this will work until the minimum length of item1, item2, item3. If you want to go longer use itertools.zip_longest instead of zip.
example with zip:
item1 = [0,1]
item3 = [2,3]
item2 = [4,5,6]
list1 = list(zip(item1, item2, item3))
[(0, 4, 2), (1, 5, 3)]
example with itertools.zip_longest:
from itertools import zip_longest
item1 = [0,1]
item3 = [2,3]
item2 = [4,5,6]
list1 = list(zip_longest(item1, item2, item3))
[(0, 4, 2), (1, 5, 3), (None, 6, None)]
Add another set of []'s to your code:
list1 = []
list1.append([[item1[i], item2[i], item3[i]] for i in range(len(item1))])
Note that this assumes that item1, item2 and item3 are all the same length
Alternately, for an exact match of your expected output, use the following:
list1 = [[item1[i], item2[i], item3[i]] for i in range(len(item1))]
Example data and output
item1 = [1, 2, 3]
item2 = ["A", "B", "C"]
item3 = [0.1, 0.2, 0.3]
list1 = [[item1[i], item2[i], item3[i]] for i in range(len(item1))]
print(list1)
>>> [[1, 'A', 0.1], [2, 'B', 0.2], [3, 'C', 0.3]]
Using .append(), the list comprehension becomes:
for i in range(len(item1)):
list1.append([item1[i], item2[i], item3[i]])
However, if you want to use a list comprehension and still append the newly created lists onto list1, use += rather than .append():
list1 += [[item1[i], item2[i], item3[i]] for i in range(len(item1))]
.append() adds the given item onto the end of the list. += will instead add each sublist individually.
If on python 2 just do zip without list:
zip(item1, item2, item3)
Demo:
item1 = [1, 2, 3]
item2 = [4,5,6]
item3 = [7,8,9]
print(zip(item1, item2, item3))
Output:
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]
list(zip(item1, item2, item3))?a = [item1, item2, item3]