I am wondering how to put a tuple into an array? or is it better to use arrays in array for the design of the program rather than a tuple in an array? please advice me. thank you
3 Answers
One thing to keep in mind is that a tuple is immutable. This means that once it's created, you can't modify it in-place. A list, on the other hand, is mutable -- meaning you can add elements, remove elements, and change elements in-place. A list has extra overhead, so only use a list if you need to modify the values.
You can create a list of tuples:
>>> list_of_tuples = [(1,2),(3,4)]
>>> list_of_tuples
[(1, 2), (3, 4)]
or a list of lists:
>>> list_of_lists = [[1, 2], [3, 4]]
>>> list_of_lists
[[1, 2], [3, 4]]
The difference is that you can modify the elements in the list of lists:
>>> list_of_lists[0][0] = 7
>>> list_of_lists
[[7, 2], [3, 4]]
but not with the list of tuples:
>>> list_of_tuples[0][0] = 7
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
To iterate over a list of tuples:
>>> for (x,y) in list_of_tuples:
... print x,y
...
1 2
3 4
3 Comments
iCezz
i just want to store value like text and ID into tuple or list but i want to check it with another for loop. instead of using a for loop in a for loop. i am thinking to use arrays in array. But was pretty confuse whether should i use tuples in list or lists in a list. I am not very good at designing the structure of the design therefore i am asking for advice and opinion
jterrace
@iCezz I added an example of how you can easily iterate over a list of tuples without multiple for loops.
iCezz
i think this is a good idea, in this case i can retrieve the value inside a tuple easily and faster without having worry that the data will be changed. thanks again
if you are talking about list, you can put anything into it, even different types:
l=[10,(10,11,12),20,"test"]
l[0] = (1,2,3)
l.append((4,5))
l.extend((21,22)) #this one adds each element from the tuple
if you mean array, no python arrays don't support tuples.
1 Comment
iCezz
thank you for the advice. this is what i mean tuple in an array. basicly it store many tuples in a list. but i thought tuples does not have method therefore i believe that it will add into the list. Thanks for sharing
a = [ ('b', i , "ff" ) for i in range(1,5)]
1 Comment
angs
The OP asked for an array, but this returns a list.
liston an actualarray?