通过python中的csv按键查找平均值

Question

我有一个简单的2列csv，需要找到每个键的平均值 即 输入csv

A,2
B,3
A,1
C,2
B,2
D,4
C,2

必需的输出

{'A': 1.5, 'B': 2.5, 'C': 2, 'D': 4}

到目前为止的代码：

pythoncsvfile = open("data.csv") 
csv_reader = csv.reader(csvfile, delimiter=',') 
for row in csv_reader: 
    print (row[0],row[1])

Answer 1

选项A

使用csv

import csv
import collections

out = collections.defaultdict(list)
with open('file.csv') as f:
    for line in csv.reader(f):
        out[line[0]].append(int(line[1]))

for k in out: 
    out[k] = sum(out[k]) / len(out[k])

print(dict(out))

{'A': 1.5, 'B': 2.5, 'C': 2.0, 'D': 4.0}

选项B

使用pandas

import pandas as pd

df = pd.read_csv('file.csv', header=None, names=['Key', 'Value'])
out = df.groupby('Key').mean()

print(out.Value.to_dict())

{'A': 1.5, 'B': 2.5, 'C': 2.0, 'D': 4.0}

Answer 2

我认为您可以使用以下代码：

import csv
from collections import OrderedDict

data = OrderedDict()

with open('data.csv', 'rb') as csvfile:
    content = csv.reader(csvfile, delimiter=',')
    for index, value in content:
        if ( not data.has_key(index) ):
            #initialize
            data[index] = {'times':1, 'total':float(value)}
        else:
            #index already present
            data[index] = {'times': data[index]["times"]+1, 'total':data[index]["total"]+float(value)}

def average(data):
    results = OrderedDict()

    for index, values in data.iteritems():
        results[index] = values["total"]/values["times"]

    return results

print average(data)

您的数据的示例结果：

OrderedDict([('A', 1.5), ('B', 2.5), ('C', 2.0), ('D', 4.0)])

HTH