使用Python从CSV文件创建嵌套字典
我有一个csv文件“input.csv”,其中包含以下数据使用Python从CSV文件创建嵌套字典,python,csv,dictionary,Python,Csv,Dictionary,我有一个csv文件“input.csv”,其中包含以下数据 UID,BID,R U1,B1,4 U1,B2,3 U2,B1,2 我希望上面的内容看起来像下面的字典;按UID键分组,BID和R作为嵌套字典值 {"U1":{"B1":4, "B2": 3}, "U2":{"B1":2}} 我有以下代码: new_data_dict = defaultdict(str) with open("input.csv", 'r') as data_file: data = csv.DictRea
UID,BID,R
U1,B1,4
U1,B2,3
U2,B1,2
我希望上面的内容看起来像下面的字典;按UID键分组,BID和R作为嵌套字典值
{"U1":{"B1":4, "B2": 3}, "U2":{"B1":2}}
我有以下代码:
new_data_dict = defaultdict(str)
with open("input.csv", 'r') as data_file:
data = csv.DictReader(data_file, delimiter=",")
headers = next(data)
for row in data:
new_data_dict[row["UID"]] += {row["BID"]:int(row["R"])}
上面提到了一个明显的错误
TypeError: cannot concatenate 'str' and 'dict' objects
有办法吗?使用常规的
dict()
可以使用get()
初始化一个新的子dict,然后填充它
import csv
new_data_dict = {}
with open("data.csv", 'r') as data_file:
data = csv.DictReader(data_file, delimiter=",")
for row in data:
item = new_data_dict.get(row["UID"], dict())
item[row["BID"]] = int(row["R"])
new_data_dict[row["UID"]] = item
print new_data_dict
另外,您对
next(data)
的调用是多余的,因为头被自动检测并从结果中剥离。使用常规的dict()
可以使用get()
初始化新的子dict,然后填充它
import csv
new_data_dict = {}
with open("data.csv", 'r') as data_file:
data = csv.DictReader(data_file, delimiter=",")
for row in data:
item = new_data_dict.get(row["UID"], dict())
item[row["BID"]] = int(row["R"])
new_data_dict[row["UID"]] = item
print new_data_dict
此外,您对
next(data)
的调用是多余的,因为头被自动检测到并从结果中剥离出来。这是使用defaultdict的更有效版本:
from collections import defaultdict
new_data_dict = {}
with open("input.csv", 'r') as data_file:
data_file.next()
for row in data_file:
row = row.strip().split(",")
new_data_dict.setdefault(row[0],{})[row[1]] = int(row[2])
这是一个使用defaultdict更高效的版本:
from collections import defaultdict
new_data_dict = {}
with open("input.csv", 'r') as data_file:
data_file.next()
for row in data_file:
row = row.strip().split(",")
new_data_dict.setdefault(row[0],{})[row[1]] = int(row[2])