I would like to get such a result [2,4,5,6,7], how can do that? Now i get this: [7]
list1 = [1,3,4,5,6]
for i in range(len(list1)):
l = []
# list1[i] = list1[i] + 1
s = list1[i] + 1
l.append(s)
print(l)
2 Answers
you can use list comprehension
list1 = [1,3,4,5,6]
newlist = [x+1 for x in list1]
print(newlist)
Comments
If you want to use a loop, you need to put l = [] ahead of it - otherwise you're reintializing it as an empty list at each loop iteration,
list1 = [1,3,4,5,6]
l = []
for el in list1:
l.append(el + 1)
print(l)
Notice that this code directly loops through elements of list1. This is a preferred way for lists and any other iterables. I recommend you use it whenever practical/possible.
As an alternative to list comprehensions and loops, you can also use a map with a lambda,
list1 = [1,3,4,5,6]
new_list = list(map(lambda x: x+1, list1))
print(new_list)
Note, however, that in most situations, including this one, list comprehension is a better choice. For reasons and details, look up this post.
2 Comments
wjandrea
It's worth adding that there's no reason to use
list(map(lambda)) all together. It's shorter and clearer to use a list comprehension: [x+1 for x in list1]. I wrote an answer about this with some more details.
atru
@wjandrea Thank you! I thought there may be some performance benefits, otherwise in a situation like this I myself would use a comprehension. Though I use maps for type conversions like in your example. I added the map solution as an alternative, for completeness.
l =[]for each iteration so you end up with a single element list with the last value ofs. Putl = []just afterlist1 = [1,3,4,5,6]and it will work. Also you can simplify tofor i in list1: ... s = i + 1