How to loop through dictionary objects in rust?

Question

I have a dictionary which in python I can iterate using

data = {"one":1,"two":2,"three":3,"four":4,....."two hundred":200}

for i,j in data.items():
    print(i,j)

Is there any way I can use the same object and iterate over the keys and values in rust?

for (i, j) in data (i and j are owned values) or for (r, s) in &data (r and s are references) — trent
– trent, Commented Feb 18, 2021 at 13:23
Are you asking about Rust syntax for the same thing? Or by "same object" do you mean accessing the Python object from Rust using PyO3 or something? — kmdreko
– kmdreko, Commented Feb 18, 2021 at 13:24

Teymour · Accepted Answer · 2022-08-23 12:03:57Z

9

I'm assuming you're after a way to do this in Rust.

Rust's analogue to a Python dictionary is a HashMap.

Unlike Python's dictionaries HashMaps are statically typed (i.e. all the keys must have the same type, and all the values must also share the same type) – to create a new HashMap you want something like:

use std::collections::HashMap;

fn main() {
  let mut hashmap: HashMap<String, i32> = HashMap::new();
  hashmap.insert("one".to_string(), 1);
  for (key, value) in hashmap {
      println!("{} {}", key, value);
  }
}

Which outputs:

one 1

Playground link

If you want to load the object from Python into Rust, there are a couple of options

You can serialize the object in the Python process and then use serde to deserialize it on the Rust side.
You can bind to CPython (e.g. using PyO3).

edited Aug 23, 2022 at 12:03

answered Feb 18, 2021 at 14:36

Teymour

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Comments

Eka · Accepted Answer · 2021-02-19 05:30:43Z

3

This works for me

use serde_json::json;

fn main() {
          
    let data = json!({"one":1,"two":2,"three":3,"four":4});    

    for (key, value) in data.as_object().unwrap(){
        println!("{:?} : {:?}",key,value.as_u64().unwrap());
    }
}

answered Feb 19, 2021 at 5:30

Eka

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1 Comment

valentinmk Over a year ago

However, HashMap is a direct replacement of a Dicts from Puthon, your solution looks most "pythonic" analog to what dicts feels in Python. Thx!

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