Questions tagged [hashmap]
A data structure that uses a hash function to map identifying values, known as keys, to their associated values
hashmap
15,294
questions
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32
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Using a str variable as a key for a map always returns null
I am trying to use a Map without success.
I have whittled it down to a bare-bones case:
I create a Map with four entries:
("fruit", 25)
("veg", 30)
("baked", 35)
("...
0
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0
answers
47
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How can I estimate the difference in performance of a HashMap lookup vs List iteration in Kotlin?
I am working on an application that needs to map pdf documents to corresponding json data files (see: Kotlin data structure for efficient lookup of nested data for more details). In trying to ...
- 1,663
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Compare two maps where the values are class objects [closed]
I'm trying to compare two hashmaps where the values are class objects. I know the .equals() for the class can be overridden so it would compare the values rather than instances but what if the class ...
- 23
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21
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How can I make hashing algorithm for code snippets?
I would like to make an algorithm, which can detect code snippets when iterating through source codes, based on some hashing algorithms.
So for example, here is that short code snippet from a fragment ...
- 298
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5
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Grouping 2D data using Python
class Point:
def __init__(self, x=None, y=None):
self.x = x
self.y = y
self.xy_list = [x, y]
def __eq__(self, other):
if isinstance(other, Point):
...
- 1
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2
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39
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How to filter and clone HashMap in Rust? [duplicate]
I've got a simple task: filter existing HashMap and clone it into a new variable in Rust.
The code I've tried:
let numbers: HashMap<u32, u32> = HashMap::from([
(1, 10),
(2, 20),
(3, ...
- 621
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1
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38
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Get HashMap value from object [duplicate]
I have a json like this
{
"data": {
"category": {
"name_en": "Trend",
"style": "normal"
},
"items"...
- 23
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1
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42
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What does an "entry" refer to in a Hashmap? Does it mean the quantity of filled buckets, or the overall quantity of keys?
I am following along with The Odin Project.
They state "The product of these two numbers (load factor and current capacity) gives us a number, and we know it’s time to grow when there are more ...
- 13
5
votes
1
answer
142
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Need to understand map.get() method after Overriding hashCode and equals in Java
I have overridden the hashCode and equals methods as below, and I want to understand the implementation of Map get method.
public class Student{
String name;
Student(String s){
this....
- 274
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1
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67
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Is ConcurrentHashMap needed, if I will only use get() method
I created an enum that includes 4 address formats. I know which country uses which format, and I'm trying to create a HashMap that will include countries as key, and formats as value. I want to get ...
- 11
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98
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Java List.of() as key in HashMap?
I know that in general, you should only use immutable objects as a key to a hashmap since if their address or their contents change, then the hash breaks. This is one of the reasons why a normal List ...
- 51
-3
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0
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39
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How to know if element exists in HashMap [duplicate]
I have a map that is already populated, when calling map.get(key), if element against that key exists it returns its corresponding value which can be null and if not then still null. I want to know ...
-2
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1
answer
55
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My multi threaded rayon Rust loop can't outperform my Signlethreaded loop
I've been creating a function that is supposed to a BigUint into the base 1048576. I've been paralyzed by a problem I'm not quite sure how to solve.
I originally made a single threaded varient but on ...
-2
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1
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66
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My HashMap which contains new Doctor keeps overriding the previous one whenever I use addDoctor method
I use HashMap to store String followed by object Doctor, where the String is the copy of code in Doctor.
At first I thought it just some problem with checking condition and throw Exception but it not.
...
- 11
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45
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I'm confused about how HashMap and HashSet manage Multiple Keys or Values [duplicate]
I have very low understanding in hashMap and hashSet internal functioning and i need help!
So:
HashMap:
I can't put two objects with same keys, So when i have object A and B, the first one has,
for ...
