如何从CSV文件读取多个记录？

Question

我有一个csv文件l__cyc.csv ，其中包含以下内容：

trip_id, time, O_lat, O_lng, D_lat, D_lng
130041910101,1300,51.5841153671,0.134444590094,51.5718053872,0.134878021928
130041910102,1335,51.5718053872,0.134878021928,51.5786920389,0.180940040247
130041910103,1600,51.5786920389,0.180940040247,51.5841153671,0.134444590094
130043110201,1500,51.5712712038,0.138532882664,51.5334949484,0.130489470325
130043110202,1730,51.5334949484,0.130489470325,51.5712712038,0.138532882664

我正在尝试使用以下方法提取单独的值：

with open('./l__cyc.csv', 'rU') as csvfile:
    reader = csv.DictReader(csvfile)
    origincoords = ['{O_lat},{O_lng}'.format(**row) for row in reader]
with open('./l__cyc.csv', 'rU') as csvfile:
    reader = csv.DictReader(csvfile)
    trip_id = ['{trip_id}'.format(**row) for row in reader]
with open('./l__cyc.csv', 'rU') as csvfile:
    reader = csv.DictReader(csvfile)
    destinationcoords = ['{D_lat},{D_lng}'.format(**row) for row in reader]

如果origincoords应为51.5841153671, 0.134444590094 ，
trip_id应该是130041910101 ，而destinationcoords应该是
51.5718053872, 0.134878021928 。

但是，我得到一个KeyError ：

KeyError: 'O_lat'

这是简单的事情，是我误会了一些基本问题吗？

Answer 1

您只需要避免标题之间的空格

trip_id,time,O_lat,O_lng,D_lat,D_lng 

要么

reader = csv.DictReader(csvfile, skipinitialspace=True)

Answer 2

首先，您会得到密钥错误，因为密钥在您的词典中不存在。

接下来，我建议不要一次运行文件3次，而只需一次即可！

对我来说，当我将字段名添加到阅读器时，它起作用了。

import csv
from cStringIO import StringIO

src = """trip_id, time, O_lat, O_lng, D_lat, D_lng
130041910101,1300,51.5841153671,0.134444590094,51.5718053872,0.134878021928
130041910102,1335,51.5718053872,0.134878021928,51.5786920389,0.180940040247
130041910103,1600,51.5786920389,0.180940040247,51.5841153671,0.134444590094
130043110201,1500,51.5712712038,0.138532882664,51.5334949484,0.130489470325
130043110202,1730,51.5334949484,0.130489470325,51.5712712038,0.138532882664
"""
f = StringIO(src)

# determine the fieldnames
fieldnames= "trip_id,time,O_lat,O_lng,D_lat,D_lng".split(",")

# read the file
reader = csv.DictReader(f, fieldnames=fieldnames)

# storage
origincoords = []
trip_id = []
destinationcoords = []

# iterate the rows
for row in reader:
    origincoords.append('{O_lat},{O_lng}'.format(**row))
    trip_id.append('{trip_id}'.format(**row))
    destinationcoords.append('{D_lat},{D_lng}'.format(**row))

# pop the header off the list
origincoords.pop(0)
trip_id.pop(0)
destinationcoords.pop(0)

# show the result
print origincoords
print trip_id
print destinationcoords

我真的不知道您要在此达成什么目标，但是我敢肯定有更好的方法来做到这一点！