data_structure | 关于各种数据结构和算法的一些收录

I'm curious how many types there are in JS, because I have read conflicting answers from otherwise reliable sources:

If we look at the ECMAScript spec, there are 8 types:

• Undefined, Null, Boolean, String, Symbol, Number, BigInt, and Object

It seems function is counted as object.

If we look at MDN, they say there is 9 types:

Six Data Types that are primitives, checked by typeof operator:

1. undefined : typeof instance === "undefined"
2. Boolean : typeof instance === "boolean"
3. Number : typeof instance === "number"
4. String : typeof instance === "string"
5. BigInt : typeof instance === "bigint"
6. Symbol : typeof instance === "symbol"

Structural Types:

1. Object : typeof instance === "object". Special non-data but Structural type for any constructed object instance also used as data structures: new Object, new Array, new Map, new Set, new WeakMap, new WeakSet, new Date and almost everything made with new keyword;
2. Function : a non-data structure, though it also answers for typeof operator: typeof instance === "function". This is merely a special shorthand for Functions, though every Function constructor is derived from Object constructor.

Structural Root Primitive:

1. null : typeof instance === "object". Special primitive type having additional usage for its value: if object is not inherited, then null is shown;

Which one of these is correct?

I would like some direction on how i can access the data and do some modifications etc. for example accessing and listing only emails, etc please

MDN says there are nine data types in latest JS spec. I wondering if these are the only nine data types that the spec allows programmers to use.

Just to clarify, I think programmer-defined functions/constructors internally using prototypical inheritance are still Objects, so do not qualify as new data types.

Is it possible in Isabelle to define a terminating recursive function f where

• f has a single parameter of type t such that values of type t may contain maps to values of type t, and
• f performs its recursive calls on all elements in the range of such a map?

For example consider the datatype trie defined in theory Trie_Fun:

I should write a java program that contains giving values to a matrix and printing the values of a matrix recursively. I tried this code,but everytime I give the input it gives index out of border exception.If I pass one less than the number variable,it takes one less input and

I was trying to implement max-queue But a more general version with arbitrary Associative function and arbitrary data type.I did the following for the max_stack part:

I got a custom keras Model which I want to optimize for hyperparameters while having a good tracking of whats going on and visualization. Therefor I want to pass hparams to the custom model like this:

I am trying to get a JSON file parsed into a usable format so I can insert it into a SQL table.

The JSON file I have is heavily nested (and I can't get the vendor to change it at this point), and uses the same name at different levels.

I have used the following code, to start off, but it is the multi sections and potentially multiple accounts etc that has me stumped. I know I will probably need to iterate through somehow, but just not sure where to begin.

I have N entities and I want to find all combinations of size 3 for these entities. The number of combinations is so large that it's impossible to actually compute all of them. So I'm going to use a heuristic: each entity has a score equal to the (number of times this entity was used in a combination with the combination score >= threshold) / (number of times this entity was used in a combination) and I want to find a combination that has a high probability of having combination score >= threshold. (Bonus points if you can find a combination with the highest score or can prove that the score is in some top percentile.)

Note that how to compute the combination score is hard to describe without giving a lot of context behind this problem, but suffice to say it's hard to predict and not fast to compute.

Since this is an ongoing process, I want to have a data structure where I can store each combination I try so that next time I can skip over them. This data structure should also help with finding potentially high scoring combinations I haven't tried yet.

A straight forward way to do this would be: