iterator Questions

9

Solved

I have a generator function like the following: def myfunct(): ... yield result The usual way to call this function would be: for r in myfunct(): dostuff(r) My question, is there a way to ...
Fpc asked 19/1, 2011 at 21:55

17

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In terms of performance, what would work faster? Is there a difference? Is it platform dependent? //1. Using vector<string>::iterator: vector<string> vs = GetVector(); for(vector<...
Espouse asked 22/4, 2009 at 10:55

2

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I have a MongoDB table containing 500 documents: db.x.find().count() Now I'd like to iterate over the all entries. Unfortunately the following code only gives 49, instead of 500: a=0; for (s in...
Adel asked 19/1, 2015 at 22:48

4

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Given a list of pairs xys, the Python idiom to unzip it into two lists is: xs, ys = zip(*xys) If xys is an iterator, how can I unzip it into two iterators, without storing everything in memory? ...
Wizardly asked 12/6, 2015 at 14:3

4

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It can be useful to iterate over multiple variables at once, overlapping (slice::windows), or not (slice::chunks). This only works for slices; is it possible to do this for iterators, using tuples ...
Gerkman asked 9/2, 2017 at 10:59

20

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Do Python iterators have a hasnext method?
Margaretamargarete asked 27/12, 2009 at 18:4

7

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How can I select a random element in an std::set? I naively tried this: int GetSample(const std::set<int>& s) { double r = rand() % s.size(); return *(s.begin() + r); // compile erro...
Baxter asked 16/6, 2010 at 11:26

4

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I have a std::vector<std::string> m_vPaths; I iterate over this vector and call ::DeleteFile(strPath) as I go. If I successfully delete the file, I remove it from the vector. My questio...
Erhart asked 22/10, 2009 at 1:37

2

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I have the following code: import torch import numpy as np import pandas as pd from torch.utils.data import TensorDataset, DataLoader # Load dataset df = pd.read_csv(r'../iris.csv') # Extract fea...
Probationer asked 24/6, 2020 at 7:34

4

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Lets say I have a small integer array like this: {10,20,30} Now for the items of that array I want to apply the following formula: 10^(arrayLenght-1) + 20^{arrayLenght-2) + 30^{arrayLenght-3} ...
Tight asked 23/8, 2013 at 11:54

4

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Let's say I have an iterator: function* someIterator () { yield 1; yield 2; yield 3; } let iter = someIterator(); ... that I look at the next element to be iterated: let next = iter.next()...
Axis asked 11/4, 2020 at 21:58

19

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I would like to get the first item from a list matching a condition. It's important that the resulting method not process the entire list, which could be quite large. For example, the following fun...
Worse asked 2/3, 2010 at 7:11

5

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I'm trying to create a map inside a map: typedef map<float,mytype> inner_map; typedef map<float,inner_map> outer_map; Will I be able to put something inside inner map, or does iterat...
Darwen asked 21/3, 2011 at 12:15

11

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Should I use std::sort(numbers.begin(), numbers.end(), std::greater<int>()); or std::sort(numbers.rbegin(), numbers.rend()); // note: reverse iterators to sort a vector in descending or...
Depurate asked 26/1, 2012 at 20:47

11

There are multiple ways of finding out the last iteration of a for and for...in loop. But how do I find the last iteration in a for...of loop. I could not find that in the documentation. for (item ...
Britten asked 9/1, 2019 at 19:10

12

C++11 provides multiple ways to iterate over containers. For example: Range-based loop for(auto c : container) fun(c) std::for_each for_each(container.begin(),container.end(),fun) However wh...
Eddington asked 23/9, 2012 at 12:13

2

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I'm trying to figure out what is the cost of cloning iterators that originate from into_iter() in Rust, but can't find anything meaningful. Consider the code like this: let v = vec![1,2,3,4,...]; /...
Brockman asked 23/10, 2023 at 13:26

1

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Let's say we have the following nested loop: MyClass myobject; for (const std::array<int,16>& arr : myobject) { for (int i : arr) { /* do something with i */ } } where MyClass can iter...
Promptbook asked 18/10, 2023 at 16:48

3

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We are using a library by another vendor, which apparently was compiled with the wrong flags, namely _ITERATOR_DEBUG_LEVEL = 0 in 32bit-Debug-mode. While I have already filed a bug report with them...
Rubie asked 20/4, 2011 at 8:56

2

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I'm implementing an iterator that iterates over the results of a generator function rather than over a data structure in memory such as a vector or map. Reading through the final working draft for...
Smug asked 8/10, 2017 at 1:52

2

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In PHP 7.1 there is a new iterable psudo-type which abstracts arrays and Traversable objects. Suppose that in my code I have a class like the following: class Foo { private $iterable; public f...
Choli asked 24/4, 2017 at 16:46

25

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Many times I need to do things TWICE in a for loop. Simply I can set up a for loop with an iterator and go through it twice: for (i = 0; i < 2; i++) { // Do stuff } Now I am interested in do...
Frisbie asked 19/10, 2010 at 19:5

15

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I'm trying to write the Haskell function 'splitEvery' in Python. Here is it's definition: splitEvery :: Int -> [e] -> [[e]] @'splitEvery' n@ splits a list into length-n pieces. The last pie...
Alleenallegation asked 16/12, 2009 at 14:58

5

How do I convert an Iterator<&str> to a String, interspersed with a constant string such as "\n"? For instance, given: let xs = vec!["first", "second", &quot...
Ploce asked 8/5, 2019 at 3:53

1

I have a parallel code that can be reduced to basically: #include <algorithm> #include <vector> struct TKeyObjPtr; class TObj { public: virtual void Calculate(TKeyObjPtr const &...
Keary asked 4/2, 2019 at 18:16

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