>我需要一些帮助来跟踪列表中的索引。我想搜索以从列表中获取以前的元素。如果我在列表中有两个元素，我想找到前面的 5 个元素，以便将它们存储在列表中。
示例：当变量start_ch显示列表中的两个元素时 '421 Eir Sport 1', '422 Eir Sport 2' ，我想获取 '416 BT Sport 2', '417 At the Races', '418 BT Sport ESPN', '419 MUTV', '420 Chelsea TV' 的前 5 个元素以将它们存储在连接最后两个元素的列表中。
我想让它像这样显示：
['416 BT Sport 2', '417 At the Races', '418 BT Sport ESPN', '419 MUTV', '420 Chelsea TV', '421 Eir Sport 1', '422 Eir Sport 2']
以下是start_ch获取这两个元素时显示的内容：
['421 Eir Sport 1', '422 Eir Sport 2']
以下是self.channel的列表：
['101 BBC One S East', '102 BBC Two', '103 ITV', '104 Channel 4', '105 Channel 5', '106 Sky One', '107 Sky Living', '108 Sky Atlantic', '401 Sky Sports 1 UK', '402 SKY Sports 2 UK', '403 Sky Sports 3 UK', '404 Sky Sports 4 UK', '405 Sky Sports 5 UK', '406 Sky Sports News HQ', '407 Sky Sports F1', '408 Sky Sports 1 HD', '409 Sky Sports 2 HD', '410 Sky Sports 3 HD', '411 Sky Sports 4 HD', '412 Sky Sports 5 HD', '413 Eurosport 1 UK', '414 Eurosport 2 UK', '415 BT Sport 1', '416 BT Sport 2', '417 At the Races', '418 BT Sport ESPN', '419 MUTV', '420 Chelsea TV', '421 Eir Sport 1', '422 Eir Sport 2']
当我尝试这个时：
for i, start_ch in enumerate(self.channel):
if start_ch == channel:
start_ch = self.channel[i:i+7]
if len(start_ch) == 1:
start_ch = self.channel[i:i-6]
elif len(start_ch) == 2:
start_ch = self.channel[i:i-5]
elif len(start_ch) == 3:
start_ch = self.channel[i:i-4]
elif len(start_ch) == 4:
start_ch = self.channel[i:i-3]
elif len(start_ch) == 5:
start_ch = self.channel[i:i-2]
elif len(start_ch) == 6:
start_ch = self.channel[i:i-1]
print "start_ch"
print start_ch
for channels in start_ch:
print "channels_list"
channels_list.append(channels) #add chanel to list
print channels_list
除了最后两个元素之外，它不会让我从列表中获取前 5 个元素。
您能否给我看一个例子，除了最后两个元素之外，我如何从列表中获取前 5 个元素，以便将它们连接在一起以将它们存储在列表中？
像这样（可能是）：
>>> channel = ['101 BBC One S East', '102 BBC Two', '103 ITV', '104 Channel 4', '105 Channel 5', '106 Sky One', '107 Sky Living', '108 Sky Atlantic', '401 Sky Sports 1 UK', '402 SKY Sports 2 UK', '403 Sky Sports 3 UK', '404 Sky Sports 4 UK', '405 Sky Sports 5 UK', '406 Sky Sports News HQ', '407 Sky Sports F1', '408 Sky Sports 1 HD', '409 Sky Sports 2 HD', '410 Sky Sports 3 HD', '411 Sky Sports 4 HD', '412 Sky Sports 5 HD', '413 Eurosport 1 UK', '414 Eurosport 2 UK', '415 BT Sport 1', '416 BT Sport 2', '417 At the Races', '418 BT Sport ESPN', '419 MUTV', '420 Chelsea TV', '421 Eir Sport 1', '422 Eir Sport 2']
>>> to_find = ['421 Eir Sport 1', '422 Eir Sport 2']
>>> target_index = self.channel.index(to_find[0])
>>> result = channel[target_index-5:target_index] + to_find
>>> result
['416 BT Sport 2', '417 At the Races', '418 BT Sport ESPN', '419 MUTV', '420 Chelsea TV','421 Eir Sport 1', '422 Eir Sport 2']