集計処理

リストやmapなどである要素が何回ずつ出現するかカウントする処理。

集約処理の他の呼び方、頻度、キーカウント、古い値に基づいた値の更新など

https://gyazo.com/3f32b6db10645243f9f7efb03ecac378

C++

code:C++

using namespace std;

template <typename K, typename V, typename A>

void map_count (map<K, V> &mapBuff, A a){

for(auto c : a) {

if (mapBuff.count(c) == 0 ) {

mapBuff.insert(make_pair(c, 1));

} else {

auto it = mapBuff.find(c);

mapBuff.insert(make_pair(c, it->second++));

}

}

}

Rust

code:rust

fn main() {

use std::collections::HashMap;

let text = "hello world wonderful world";

let mut map = HashMap::new();

for word in text.split_whitespace() {

let count = map.entry(word).or_insert(0);

*count += 1;

}

println!("{:?}", map);

}

Python

code:python

import collections

c = collections.Counter(l)

print(c)

# Counter({'a': 4, 'c': 2, 'b': 1})

print(type(c))

# <class 'collections.Counter'>

print(issubclass(type(c), dict))

# True

print(l.count('a'))

# 4

print(l.count('b'))

# 1

print(l.count('c'))

# 2

print(l.count('d'))

# 0

code:python

S = input()

aggregate = {}

for c in S:

if (c in aggregate) == False:

else:

print(aggregate)