How to add elements in a list in list?
Question:
i am a beginner in python.
i have a list in list and i simply want to add an element in each sub-list at the last.
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
for i in a:
b = i.append(0) #want to add zero at the last of each sublist.
print(b)
each time output shows None
(Null value)
Answers:
You are almost there:
for i in a:
i.append(0) #want to add zero at the last of each sublist.
print(a)
The append modifies the existing list in the list, so no need to use the b variable
Your code is correct but your understanding of list operation is wrong
lst = [1,2,3]
print(lst.append(4)) # None as the append method will return None
print(lst) #[1, 2, 3, 4]
https://docs.python.org/3/tutorial/datastructures.html
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
for i in a:
i.append(0) #want to add zero at the last of each sublist.
print(a) # [[0, 1, -1, 2, -2, 3, -3, 4, -4, -5, 5, 8, 0], [0, 6, -6, 7, -7, 8, -8, 9, -9, -10, 10, 9, 0]]
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
x = list(map(lambda x: x + [0], a))
print(x)
i am a beginner in python.
i have a list in list and i simply want to add an element in each sub-list at the last.
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
for i in a:
b = i.append(0) #want to add zero at the last of each sublist.
print(b)
each time output shows None
(Null value)
You are almost there:
for i in a:
i.append(0) #want to add zero at the last of each sublist.
print(a)
The append modifies the existing list in the list, so no need to use the b variable
Your code is correct but your understanding of list operation is wrong
lst = [1,2,3]
print(lst.append(4)) # None as the append method will return None
print(lst) #[1, 2, 3, 4]
https://docs.python.org/3/tutorial/datastructures.html
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
for i in a:
i.append(0) #want to add zero at the last of each sublist.
print(a) # [[0, 1, -1, 2, -2, 3, -3, 4, -4, -5, 5, 8, 0], [0, 6, -6, 7, -7, 8, -8, 9, -9, -10, 10, 9, 0]]
a = [ [0, 1 ,-1, 2, -2, 3, -3, 4, -4, -5, 5, 8], [0, 6 ,-6, 7, -7, 8, -8, 9, -9, -10, 10, 9] ]
x = list(map(lambda x: x + [0], a))
print(x)