Questions tagged [iteration]
Iterations are the successive repetitions in loops such as for, foreach or while. Questions with this tag are often concerned about how to best handle a collection of data.
iteration
915
questions
931
votes
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answers
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How to remove items from a list while iterating?
I'm iterating over a list of tuples in Python, and am attempting to remove them if they meet certain criteria.
for tup in somelist:
if determine(tup):
code_to_remove_tup
What should I ...
- 50.4k
2080
votes
28
answers
1.1m
views
Why is using "for...in" for array iteration a bad idea?
I've been told not to use for...in with arrays in JavaScript. Why not?
- 57.8k
5722
votes
41
answers
5.4m
views
Loop (for each) over an array in JavaScript
How can I loop through all the entries in an array using JavaScript?
- 59.4k
1301
votes
31
answers
524k
views
Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop
We all know you can't do the following because of ConcurrentModificationException:
for (Object i : l) {
if (condition(i)) {
l.remove(i);
}
}
But this apparently works sometimes, but ...
- 227k
9
votes
3
answers
4k
views
How can I collect the results of a repeated calculation in a list, dictionary etc. (or make a copy of a list with each element modified)?
There are a great many existing Q&A on Stack Overflow on this general theme, but they are all either poor quality (typically, implied from a beginner's debugging problem) or miss the mark in some ...
- 61.2k
3989
votes
46
answers
3.4m
views
How do I efficiently iterate over each entry in a Java Map?
If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it, what is the most efficient way of going through the map?
Will the ordering of ...
- 38.9k
570
votes
15
answers
411k
views
What are iterator, iterable, and iteration?
What are "iterable", "iterator", and "iteration" in Python? How are they defined?
See also: How to build a basic iterator?
- 6,595
154
votes
8
answers
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Does pandas iterrows have performance issues?
I have noticed very poor performance when using iterrows from pandas.
Is it specific to iterrows and should this function be avoided for data of a certain size (I'm working with 2-3 million rows)?
...
- 8,945
2282
votes
7
answers
459k
views
How does PHP 'foreach' actually work?
Let me prefix this by saying that I know what foreach is, does and how to use it. This question concerns how it works under the bonnet, and I don't want any answers along the lines of "this is how you ...
- 88.4k
453
votes
21
answers
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views
Way to go from recursion to iteration
I've used recursion quite a lot during my many years of programming to solve simple problems, but I'm fully aware that sometimes you need iteration due to memory/speed problems.
So, sometime in the ...
- 9,649
657
votes
19
answers
824k
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How to iterate over a JavaScript object?
I have an object in JavaScript:
{
abc: '...',
bca: '...',
zzz: '...',
xxx: '...',
ccc: '...',
// ...
}
I want to use a for loop to get its properties. And I want to iterate ...
- 10.9k
3771
votes
7
answers
4.5m
views
Iterate through a HashMap [duplicate]
What's the best way to iterate over the items in a HashMap?
- 57.8k
164
votes
3
answers
40k
views
Are for-loops in pandas really bad? When should I care?
Are for loops really "bad"? If not, in what situation(s) would they be better than using a more conventional "vectorized" approach?1
I am familiar with the concept of "vectorization", and how pandas ...
- 397k
164
votes
23
answers
144k
views
How can you iterate over the elements of an std::tuple?
How can I iterate over a tuple (using C++11)? I tried the following:
for(int i=0; i<std::tuple_size<T...>::value; ++i)
std::get<i>(my_tuple).do_sth();
but this doesn't work:
...
1521237
721
votes
13
answers
1.3m
views
Ways to iterate over a list in Java
Being somewhat new to the Java language I'm trying to familiarize myself with all the ways (or at least the non-pathological ones) that one might iterate through a list (or perhaps other collections) ...
- 11.4k