python - Web爬网:Xpath列表索引超出范围

当我运行以下代码时，我得到列表索引超出范围的消息：

import requests
from lxml.html import fromstring

def get_values():
    print('executing get_values...')
    url = 'https://sports.yahoo.com/nba/stats/weekly/?sortStatId=POINTS_PER_GAME&selectedTable=0'
    response = requests.get(url)
    parser = fromstring(response.text)
    for i in parser.xpath('//tbody/tr')[:100]:
         **FGM = i.xpath('.//td[4]/span/text()')[0] #This runs with no error even though its has similar xpath.**
         print('FGM: ' + FGM)
         G = i.xpath('.//td[2]/span/text()')[0]
         print(G)

values = get_values()

当我运行代码时，出现以下错误消息：

 G=i.xpath('/./td[2]/span/text()')[0]
 IndexError: list index out of range

我试图使用以下语句进行调试。

print(parser.xpath('//tbody/tr/td[2]/span/text()')) #Returns list['4', '4', '3', '3', '3', '4', '4', '3', '2', '4', '3']
print(parser.xpath('//tbody/tr/td[2]/span/text()')[0]) #Returns value = 4
print(len(parser.xpath('//tbody/tr/td[2]/span/text()')[0])) # Returns value = 1

输出显示了预期值，因此我不确定其不起作用的原因。任何帮助，将不胜感激！

最佳答案

之所以失败，是因为第二个<span>中并不总是有一个<td>。这应该工作：

def get_values():
    print('executing get_values...')
    url = 'https://sports.yahoo.com/nba/stats/weekly/?sortStatId=POINTS_PER_GAME&selectedTable=0'
    response = requests.get(url)
    parser = fromstring(response.text)
    for i in parser.xpath('//tbody/tr')[:100]:
         FGM = i.xpath('.//td[4]/span/text()')[0] #This runs with no error even though its has similar xpath.**
         print('FGM: ' + FGM)
         G = i.xpath('.//td[2]/text()|.//td[2]/span/text()')[0]  # <--- Changed this
         print(G)

values = get_values()