将 CSV 数据转换为字典中的列表

Question

我有一个 CSV 文件，格式如下：

Name_1,2,K,14
Name_1,3,T,14
Name_1,4,T,18
Name_2,2,G,12
Name_2,4,T,14
Name_2,6,K,15
Name_3,2,K,12
Name_3,3,T,15
Name_3,4,G,18

我想把它转换成一个字典，其中Name_x是键，对应的数据是列表形式的值。像这样：

{'Name_1': [[2, 'K', 14], [3, 'T', 14], [4, 'T', 18]],
 'Name_2': [[4, 'T', 14], [4, 'T', 14], [6, 'K' ,15]],
...}

到目前为止，我想我必须使用 defaultdict:

from collections import defaultdict
d = defaultdict(list)

但是我如何append将数据d？我知道 defaultdict 没有 append 方法。

Answer 1

您需要使用名称作为键并附加行的切片作为值，使用普通或默认字典将没有顺序：

import csv
from collections import defaultdict

with open('in.csv') as f:
    r = csv.reader(f)
    d = defaultdict(list)
    for row in r:
        d[row[0]].append(row[1:])
print(d)

如果你想维持秩序，你需要 OrderedDict:

from collections import OrderedDict

with open('in.csv') as f:
    r = csv.reader(f)
    od = OrderedDict()
    for row in r:
        # get key/ first element in row
        key = row[0]
        # create key/list paring if it does not exist, else just append the value
        od.setdefault(key, []).append(row[1:])
print(od)

输出：

OrderedDict([('Name_1', [['2', 'K', '14'], ['3', 'T', '14'], ['4', 'T', '18']]), ('Name_2', [['2', 'G', '12'], ['4', 'T', '14'], ['6', 'K', '15']]), ('Name_3', [['2', 'K', '12'], ['3', 'T', '15'], ['4', 'G', '18']])])

如果名称已分组，您也可以使用 groupby，这将根据每行中的第一个 item/name 对元素进行分组：

import csv
from collections import OrderedDict
from itertools import groupby
from operator import itemgetter

with open('in.csv') as f:
    r = csv.reader(f)
    od = OrderedDict()
    for k, v in groupby(r, key=itemgetter(0)):
        od[k] = [sub[1:] for sub in v]

如果您使用 python3，您可以使用 *:

解压

with open("in.csv") as f:
    r = csv.reader(f)
    od = OrderedDict()
    for row in r:
        key, *rest = row
        od.setdefault(key, []).append(rest)


import csv
from collections import OrderedDict
from itertools import groupby
from operator import itemgetter

with open('in.csv') as f:
    r = csv.reader(f)
    od = OrderedDict()
    for k, v in groupby(r, key=itemgetter(0)):
        od[k] = [sub for _, *sub in v]
print(od)

Answer 2

在我的脑海中（因为我对 defaultdict 不太熟悉），这应该可以大致满足您的要求。

数据是 CSV 字符串

obj = {}

data = data.split('\n')
for row in data:
    row = row.split(',')
    if row[0] in obj:
        obj[row[0]].append(row[1:])
    else:
        obj[row[0]] = [row[1:]]

print obj

Answer 3

txtcsv="""Name_1,2,K,14
Name_1,3,T,14
Name_1,4,T,18
Name_2,2,G,12
Name_2,4,T,14
Name_2,6,K,15
Name_3,2,K,12
Name_3,3,T,15
Name_3,4,G,18"""

def save():
    with open("test.csv","w") as f:
        f.write(txtcsv)


if __name__ == "__main__":
    save()
    with open("test.csv") as f:
        d = {}
        for l in f.readlines():
            name, val = l.rstrip().split(",", 1)
            d.setdefault(name, []).append(val.split(","))
        print (d)

将 CSV 数据转换为字典中的列表

Converting CSV data to list in dictionary

python

csv

dictionary

python-3.x

defaultdict