输出必须如下:
[{'id': '1', 'first_name': 'Heidie','gender': 'Female'}, {'id': '2', 'first_name': 'Adaline', 'gender': 'Female'}, {...}
有一个代码片段可以运行,运行此要求。
with open('./test.csv', 'r') as file_read:
reader = csv.DictReader(file_read, skipinitialspace=True)
listDict = [{k: v for k, v in row.items()} for row in reader]
print(listDict)
但是,我无法理解上述代码的一些要点:
listDict = [{k: v for k, v in row.items()} for row in reader]
python如何解释这个?
编译器如何使用标题(id
,first_name
,gender
)及其值组合列表?
如何使用嵌套的for
实现此代码我读了这些答案,但我仍然不明白:
我的csv文件:
id,first_name,last_name,email,gender
1,Heidie,Philimore,[email protected],Female
2,Adaline,Wapplington,[email protected],Female
3,Erin,Copland,[email protected],Female
4,Way,Buckthought,[email protected],Male
5,Adan,McComiskey,[email protected],Male
6,Kilian,Creane,[email protected],Male
7,Mandy,McManamon,[email protected],Female
8,Cherish,Futcher,[email protected],Female
9,Dave,Tosney,[email protected],Male
10,Torr,Kiebes,[email protected],Male
你的清单理解:
listDict = [{k: v for k, v in row.items()} for row in reader]
等于:
item_list = []
#go through every row
for row in reader:
item_dict = {}
#in every row go through each item
for k,v in row.items():
#add each items k,v to dict.
item_dict[k] = v
#append every item_dict to item_list
item_list.append(item_dict)
print(item_list)
编辑(更多解释):
#lets create a list
list_ = [x ** 2 for x in range(0,10)]
print(list_)
这会返回:
[0,1,4,9,16,25,36,49,64,81]
你可以这样写:
list_ = []
for x in range(0,10):
list_.append(x ** 2)
所以在那个例子中你是'向后'读它
现在假设下一个:
#lets create a list
list_ = [x ** 2 for x in range(0,10) if x % 2 == 0]
print(list_)
这会返回:
[0,4,16,36,64]
你可以这样写:
list_ = []
for x in range(0,10):
if x % 2 == 0:
list_.append(x ** 2)
所以这不是100%倒退,但它应该是合乎逻辑的发生。希望这对你有所帮助!