I have been banging my head against this for two days now. I am new to python and programming so the other examples of this type of error have not helped me to much. I am reading through the documentation for lists and tuples, but haven’t found anything that helps. Any pointer would be much appreciated. Not looking for the
Tag: list
Assign a value to a list of variables using a loop
I can do this in C, but I haven’t come across it in Python. Say I have a few variables: and I have list of values [1, 2, 3, 4] how can I assign the values to the variables with a single loop so I get the following result: Answer While you technically can modify local variables, doing so is
Explanation of how nested list comprehension works?
I have no problem understanding this: I thought that was all, but then I found this snippet: Which makes b = [1,2,3,4,5,6]. The problem is I’m having trouble understanding the syntax in [x for xs in a for x in xs], Could anyone explain how it works? Answer Ah, the incomprehensible “nested” comprehensions. Loops unroll in the same order as
How does the max() function work on list of strings in python?
I have a list: It gives: Please also explain how it perform comparison on list of strings and list of numbers. Answer This is actually a good question and the answer varies depending on whether you’re on python2.x or python3.x … And which python implementation you’re using1. See here for a description of how python compares different types. The link
Index all *except* one item in python
Is there a simple way to index all elements of a list (or array, or whatever) except for a particular index? E.g., mylist[3] will return the item in position 3 milist[~3] will return the whole list except for 3 Answer For a list, you could use a list comp. For example, to make b a copy of a without the
Find matching values in a list of lists
I’m trying to iterate over a list of lists in python 2.7.5 and return those where the first value is found in a second list, something like this: So I would want list3 to contain [[‘aa’,1,3,7],[‘bc’, 3, 4, 4]] but instead I just get the whole of list2. Answer Try a more simple approach that is closer to what you
Access multiple elements of list knowing their index [duplicate]
This question already has answers here: Explicitly select items from a list or tuple (9 answers) Closed 7 months ago. I need to choose some elements from the given list, knowing their index. Let say I would like to create a new list, which contains element with index 1, 2, 5, from given list [-2, 1, 5, 3, 8, 5,
How can I use list comprehensions to process a nested list?
I have this nested list: I want to convert each element in l to float. I have this code: How can I solve the problem with a nested list comprehension instead? See also: How can I get a flat result from a list comprehension instead of a nested list? Answer Here is how you would do this with a nested
cross product in python of arbitrarily many lists
I know you can take the pairwise cross product of lists in the ways posted here: Pairwise crossproduct in Python but I want to take a list L and a positive integer n and return the cross-product of L with itself n times. Is there a built in way to do this or will I just have to iterate the
Convert range(r) to list of strings of length 2 in python
I just want to change a list (that I make using range(r)) to a list of strings, but if the length of the string is 1, tack a 0 on the front. I know how to turn the list into strings using but I want to be able to also change the length of those strings. Input: Output: And if