TypeError：'generator'对象没有属性'__getitem__'

Question

我编写了一个应该返回字典的生成函数。但是当我尝试打印字段时，我收到以下错误

print row2['SearchDate']
TypeError: 'generator' object has no attribute '__getitem__'

这是我的代码

from csv import DictReader
import pandas as pd
import numpy as np


def genSearch(SearchInfo):
    for row2 in DictReader(open(SearchInfo)):
        yield row2

train = 'minitrain.csv'

SearchInfo = 'SearchInfo.csv'

row2 = {'SearchID': -1}

for row1 in DictReader(open(train)):
    if 'SearchID' in row1 and 'SearchID' in row2 and row1['SearchID'] == row2['SearchID']:
        x = deepcopy( row1 )
        #x['SearchDate'] = row2['percent']
        x.update(row2)    
        print 'new'
        print x
    else: 
        #call your generator
        row2 = genSearch(SearchInfo)
        print row2['SearchDate']

Answer 1

Generator返回一个迭代器，你明确需要在它上面调用它。

你的最后一行代码应该是 -

rows_generator = genSearch(SearchInfo)
row2 = next(rows_generator, None)
print row2['SearchDate']

理想情况下，我们在循环中使用迭代器，它会自动为我们做同样的事情。

Answer 2

生成器必须是迭代器，而不是 iterables 。 Iterables包含  __item__()和__getitem__()方法，而迭代器包含next() / __next__()方法（python版本2.x / 3.x）。