擅长:python、mysql、java
<p>你可以用一个简单的例子来解决你的问题</p>
<pre><code>oblist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]
start_index = 7
for x in range(len(oblist)):
x= x+1
if start_index - x < 0:
i = None
else:
i = oblist[start_index - x]
if start_index + x > len(oblist) - 1:
j = None
else:
j = oblist[start_index + x]
if j == None and i == None:
break
else:
print(i , j)
Output
6 8
5 9
4 10
3 11
2 12
1 13
0 14
None 15
None 16
</code></pre>