我原以为我对python相当在行,但这个问题让我很为难。你知道吗
以下代码起作用
import csv
f = open("potholes.csv")
count = 0
for row in csv.DictReader(f):
addr_bits = row['STREET ADDRESS'].split()
street_num = addr_bits[0:1]
count += 1
print type(addr_bits)
print addr_bits
print street_num
print "completed processing " + str(count) + " records"
输出:
<type 'list'>
['2519', 'S', 'HALSTED', 'ST']
['2519']
completed processing 378033 records
然而,这个代码给出了一个错误
import csv
f = open("potholes.csv")
count = 0
for row in csv.DictReader(f):
addr_bits = row['STREET ADDRESS'].split()
street_num = addr_bits[0]
count += 1
print type(addr_bits)
print addr_bits
print street_num
print "completed processing " + str(count) + " records"
输出:
Traceback (most recent call last):
File "/home/linux/PycharmProjects/potholes/potholes", line 7, in <module>
street_num = addr_bits[0]
IndexError: list index out of range
Process finished with exit code 1
唯一的区别是,第一个代码使用[0:1]访问这个列表,第二个代码使用[0],但我认为这是访问列表的合法方式。你知道吗
这是因为有时行['STREET ADDRESS']是空的,使得
row['STREET ADDRESS'].split()
返回一个空列表您可以使用片访问空列表,但不能访问特定于索引的元素。你知道吗
举个例子:
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