Questions tagged [array]
An array is a systematic arrangement of similar objects, usually in rows and columns.
213
questions
-2
votes
0answers
48 views
C# How to swap sections of data in two different 2d arrays of the same length, forming a third 2d array containing newly swapped data [closed]
I am extremely new to coding and I am currently learning C# on my own. I have searched around but I cannot find what I am looking for. I may not be searching for the correct terms.
I am wondering how ...
0
votes
0answers
61 views
Best choice for a holding large number of objects in java
I have a set of array, containing a large number of objects (products), which has lately grown so large, searching in it takes about a minute, which is considered too long, since one search is ...
1
vote
2answers
153 views
JS - two array filters vs. one forEach?
I've had a question for a while. I know that the Array prototype method filter is generally preferred over forEach, and I believe it is typically faster at the job as well.
But what about if I have ...
1
vote
1answer
190 views
Do C++ compilers optimize/pack small data types (e.g. boolean values)?
This occurred to me when looking at stencil computations in numpy. This python library compiles compute-intensive components, so I believe that it's a valid example. Here making selections on an array ...
-2
votes
2answers
78 views
Comparing and replacing values in an array [closed]
I am currently working on a program that replaces the value in an array if the value next to it is the same as the current value. So If the array is [0,0,0,1,0,1,0], when the program runs it'll turn ...
4
votes
2answers
174 views
Arrays vs Maps for listing items that have a unique id
I've been finding that for a lot of code I've been writing recently, it naively might look like this:
Array approach:
const options = [
{
id: 'red',
label: 'Red',
data: '#f00'
...
6
votes
7answers
972 views
What is the difference between an index and an offset?
I am looking to understand the difference between the words index and offset.
I have never seen "offset" in reference to lists/arrays/etc in programming. I have only seen index.
To me, these ...
0
votes
1answer
98 views
how to store the data for function f(time,length)
I have a function which has discrete time step ,discrete length from origin . These two give height of the function. For example at time 1.2sec , and length 5.5cm from origin height is 10cm. The step ...
-4
votes
1answer
123 views
A good metaphor for “lists” (arrays)? [closed]
When teaching students Python lists (which are more like arrays, not linked-lists) I'd like to use metaphor of list being a collection of boxes put in row.
But this doesn't work well:
indexes are ...
8
votes
2answers
2k views
Is there a sensible way to sort coordinates?
Sorting is generally used to solve problems where distance between elements matters. A sorted list/array has the convenient property that the smaller the difference between the indices of any two ...
0
votes
3answers
380 views
How to guarantee an ID is unique in a non-UUID set of values?
I would like to have IDs of different sizes from the alphabet 0-9. So I have 5-length IDs as in 10000 or 13531, etc.. I have 10, 15, 20, up to 39 digit strings (the size of a UUID). I would like to ...
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votes
1answer
81 views
Are jagged arrays lvalue or not?
When I was study lvalue i see that
C expression can be lvalue if a subscript ([]) expression that does not evaluate to an array.
(from
https://docs.microsoft.com/en-us/cpp/c-language/l-value-and-...
3
votes
1answer
139 views
What is the expected performance of While loops using `array.pop()` assignment vs other methods
Recently I was asked to refactor some code that leverages JavaScript's array.reduce() method because other developers felt the code hard to read. While doing this I decided to play around with some ...
2
votes
2answers
189 views
sizeof(a)/sizeof(a[0]) vs sizeof(a)/sizeof(t) where t is type in C from K.N.King
I'm trying to understand why sizeof(a)/sizeof(t) is inferior for getting the length of an array to sizeof(a)/sizeof(a[0]) if just as it's possible to have different types, my elements could also be of ...
-2
votes
1answer
455 views
Generate large Excel files and response from API
I need to generate a large Excel file (something around 50 megs) and send response to another API which will provide it to the front end for a download option.
My question is if it will be better to ...
1
vote
1answer
87 views
How should I approach the comparison of two BMP images?
I am currently writing a Python program that retrieves the pixels from two BMP files and finds the percent difference between them (without using the Pillow library for the purpose of learning). I can ...
-3
votes
1answer
340 views
C# is fantastic, if only List 'd respect Remove&Return [closed]
In the domain of system-modeling (e, systemVerilog, matlab, phyton), lists are obsoleting arrays, stacks and queues(*) altogether. Other domains that use python, perl and ruby have that same mindset, ...
1
vote
3answers
252 views
Are 'array elements' and 'array values' the same?
Array := {"title": "Book Title", "author": "John Doe"}
Some people use the following terminology:
title and author are keys.
Book Title and John Doe are values.
"title": "Book Title" and "author": ...
-1
votes
1answer
93 views
Algorithm that maps consecutive whole numbers to sets of numbers
Where would I begin if I wanted to develop an algorithm that maps consecutive whole numbers to a long list of unique sets of whole numbers. For example:
0 = {0, 0, 0}
1 = {0, 0, 1}
2 = {0, 0, 2} ...
1
vote
1answer
40 views
Determine array of objects collective identity and be able to inspect it
I have an array of objects and I'm trying to see, through each request, whether or not a new member appeared in my collection.
The way I currently do it is, I require each member of the collection to ...
1
vote
3answers
1k views
Does the gcc optimize out local arrays the same way it would optimize out a local variable?
If I write this code in a function:
void func(void)
{
int x = 0;
int y = 3724832+x;
}
It would (probably) optimize the variable y out because it isn't being used. Even if I'm wrong about ...
0
votes
1answer
172 views
PHP: simple class for storing read-only data structure, array alternative
I need to share some associative data between different parts of my application with two requirements:
immutability (so read-only)
safety against mispelling or unavailable index inside the data
...
2
votes
1answer
52 views
At what size array in Swift would you consider switching to CoreData?
I've developed a reading tracking app in Swift and for simplicity's sake I used arrays for my model. It stores some data about the books a user reads and a small image of the cover. I save them to ...
1
vote
0answers
40 views
is it better to have tracking fields that are maintained separately for arrays? [duplicate]
I wasn't sure exactly how to word this question, but basically, I have a struct stNeuralLayers (for a neural network I'm playing around with) with fields that are matrices (such as a double[,] ...
0
votes
2answers
266 views
Should execution continue if array is empty?
Just a general programming best practices question.
If I have a function like that takes in an array of items and the function then calls a series of other functions which filter and act on the items ...
2
votes
1answer
396 views
How should I define hardcoded strings with some variable parts? Reuse more characters? Or keep the whole sentence?
for example, sometimes I need to define a hardcoded string with some variable parts, I often have trouble to choose the style:
style 1 : reuse every characters when possible
showMessage(num){
let ...
2
votes
2answers
355 views
Should I use Array or Set if both can be used to finish my task?
for example, Suppose I have a 2d array:
let filterArr=[
[1,1,0,1,1],
[0,1,1,1,0],
[1,1,0,1,0]
];
I want to find and store the index of column that all are 1, i.e.:position 1 and 3, and the ...
0
votes
1answer
158 views
For arrays, should I use the first position to store the selected element, instead of variable like “selectedIndex”, if possible?
For example, I have a toggle button, which would show the current selected element, and would show next element when it is clicked, and it can loop back to first element. I have 2 ways to store the ...
2
votes
2answers
157 views
Should special case be inside or outside the for loop here?
For example, suppose I have 2 arrays:
let arr1=[5,2,1];
let arr2=["abcde","ab","a"];
my work is simple : to check if length of strings in arr2 are larger than corresponding element with same index ...
3
votes
2answers
123 views
Should I move tasks which is just for a specific element only out of for loop?
For example, I have a for loop, which element 0 has additional function to run compared with other elements, my question is, should the additional function be:
1.place inside for loop
for(int i=0;i&...
2
votes
3answers
1k views
How do I put objects of different types derived from a common base in the same array? [closed]
I have two classes called Player and Enemy both inheriting from a class called GameObject, how do I store them both in an array of type GameObject while still keeping their own unique information?
I ...
3
votes
1answer
116 views
Array rotation algorithm
I'm developing an application which sends quotes to clients via email.
Since quotes are obtained from various resources (per each client) they end up in a single array which is then used as a source ...
-1
votes
2answers
1k views
How does a dynamic array access work?
In C if i declare
int x[4]
Which tells me its an integer array with each array element size fixed of size 4.
So after initialization when I access x[3] : address of array +element size which is 2 *...
1
vote
2answers
96 views
Linked-list iteration patterns
If you have a linked-list, where the items are not necessarily close to each other in memory, wondering if it is (in general) better/worse/no difference to do the following.
Say you want to iterate ...
3
votes
1answer
247 views
What is best practice for handling mapping arbitrary depth in arrays?
I have a set of data:
id | name | parentid
------------------------
1 | parent | 0
2 | child | 1
3 | child | 1
4 | parent | 0
5 | child | 4
6 | subchild | 5
7 | child | 4
...
2
votes
2answers
5k views
How exactly indexing works in arrays?
I only know that index is faster but don't know why is it faster.
Suppose I have an array int[] a = {2,3,6,7}. Then I will try to find the element at a[3] and the speed of this will be O(1). Why? How ...
11
votes
2answers
2k views
How did the custom of using square brackets for array elements develop?
Many programming language use the syntax a[i] to refer to the i'th element of an array, sequence, or vector a - specifically, C and Pascal (from the late 1960s and early 1970s) do this. On the other ...
1
vote
2answers
382 views
Are there any use cases for List when Deques and Arrays are available?
I've been thinking about this over the past few weeks, and I've come up with no good arguments. My perspective is from Java, but if anyone has any language-specific cases outside of this language, I'...
3
votes
4answers
102 views
Store csv data as rows or columns in view of the needed processing?
Assume I have some data a csv-Files like
ObjectName, PropertyA, PropertyB, PropertyC
"Name1", 3, 1, 4
"Name2", 1, 5, 9
"Name3", 2, 6, 5
...
and a typical question I want to answer would be
For ...
5
votes
3answers
2k views
Is “Array[1]” the first element or second element in the array?
Following the reading of the question Why are zero-based arrays the norm?, I wonder about the terms to use for referring to specific array elements, in the perspective of linguistic reading of ...
0
votes
1answer
95 views
What is the name or description of my technique for filtering items in array? [closed]
I've tried posting this question on StackOverflow but they told me to try it here since it's not so specific. I'd like to know the name of the algorithm or technique of following implementation. I ...
1
vote
0answers
62 views
How should I store a frequently accessed array with an unknown number of elements in mongodb?
I have a simple "Index" object defined as follows:
{
"position": 4,
"value": 345
}
And I'm trying to figure out the best way to store this object in a mongo database, assuming that:
The "...
-1
votes
1answer
1k views
Why is it possible to access an array out of bounds with negative indexes much further than with positive indexes?
I have written two small programs in which I declare a very small array.
Then I try to access values out of bounds.
The interesting thing I noticed that when I try to decrement the index I can ...
1
vote
2answers
165 views
Is it unnecessary to have a method that merely loops through an array and calls another method with each item?
For example, if there's multiple lines to be drawn, I could do
function drawLines(lines) {
lines.forEach(function (line) {
drawLine(line);
});
}
function drawLine(line) {
//...
}
...
2
votes
3answers
2k views
Return array pointers vs. populating an array inserted as a parameter?
Which is better? I noticed the latter is used in a lot of C code. People will typically malloc an array, and then pass that as a parameter to a function, which will then populate it. Whereas in Java, ...
-4
votes
2answers
2k views
How to create a method that takes array list as argument?
To create a method that takes an array as an argument, you would do this:
public static void printAges(int[] age) { // prints ages to screen
for (int x = 0; x < age.length; x++) {
...
2
votes
1answer
152 views
Handling out of bounds requests in embedded C library
We're currently building a library in C that configures itself from tables in EEPROM.
This leaves the possibility however that some caller requests a field that is out of bounds, and the question ...
1
vote
1answer
810 views
Merging algorithm for overlapping intervals
I have been searching for an efficient algorithm to merge overlapping intervals on a dynamic array of intervals. For example, (start time, end time) wise,
[(1, 2), (4, 8), (3, 10)]
becomes
[(1, 2)...
0
votes
1answer
951 views
Lower bound for finding a value in sorted array
Suppose we have a sorted array of unique elements, A[n]. I am trying to find the lower bound for finding a specific element x in the array. I suspect the lower bound to be log_2(n+1).
I tried to use ...
2
votes
4answers
1k views
Fastest algorithm of dividing array into positive and negative numbers
Given array of integers I am trying to design the fastest algorithm that swaps the elements such that at the end : all negative elements are on the left and then the positive elements, for example, ...
