python - Python Dictreader 对字段名进行排序

Question

我有一个包含内容的 .csv 文件（示例）

Attributes,Description,Dial-Up
4,2,0.2
3,1,0.4

使用字典阅读器：

dictreader = csv.DictReader(open(filename, "rb"), delimiter=',')
dictdata = {}
count=0
for row in dictreader:
    dictdata[count]=row
    count=count+1

并显示在表格中或使用作家我会得到：

Dial-Up,Attributes,Description
0.2,4,2
0.4,3,1

那么如何对字段名进行排序呢？

Answer 1

将DictReader字段（dict 键）存储在名为的属性中fieldnames：

fields = dictreader.fieldnames
print(fields)
# ['Attributes', 'Description', 'Dial-Up']

因此，要按此顺序打印行值：

print(','.join(fields))
for row in dictreader:
    print(','.join(row[field] for field in fields))

产量

Attributes,Description,Dial-Up
4,2,0.2
3,1,0.4

---

或者，使用@JonClements 的想法：

import operator
fields = dictreader.fieldnames
getfields = operator.itemgetter(*fields)
for row in dictreader:
    print(','.join(getfields(row)))

使用的动机operator.itemgetter是它比使用列表理解更快：

In [70]: %timeit getfields(row)
10000000 loops, best of 3: 174 ns per loop

In [71]: %timeit [row[field] for field in fields]
1000000 loops, best of 3: 272 ns per loop