Rs
Collections & the Standard Library
Module 5HashMap & BTreeMapLesson 4 of 820 min

HashMap Portfolios

Aggregate fills into net positions by ticker.

HashMap

rust
use std::collections::HashMap;
let mut port = HashMap::new();
port.insert("AAPL".to_string(), 100.0);

entry API

rust
*port.entry(t).or_insert(0.0) += qty;

Avoids double lookup when aggregating trades.

Challenge

Track average price per ticker from (ticker, qty, px) fills.

Tips
  • entry API is idiomatic
  • HashMap order is random
  • String keys when owned

Try it live

HashMap PortfoliosRust 2021
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Output
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