从元组数组中创建一个List

Question

我在Python2.7中编写脚本。我有一个像g_var = '1' l_var = '1' print g_var, l_var # prints 1, 1, the values of the global variables def my_func(): global g_var # the keyword global tells that we want to change the global variable g_var g_var = '2' l_var = '2' print g_var, l_var # prints 2, 2, the first being the value of the global variable, the second being the local declared variable l_var. my_func() print g_var, l_var # prints 2, 1, again the values of both global declared variables 这样的数组，我想从每个子集的第一个元素中创建一个列表，如：

k = ((12,12.356,40.365),(458,12.2258,42.69))

虽然我遇到了错误for i in K: l = k[i][0] 请您告诉我如何提出解决方案？

Answer 1

您正尝试按k之类的元组访问k[(12,12.356,40.365)][0]元组项，而有序序列项应通过其位置/索引访问（例如k[0][0]）。< / p>

使用list comprehension从每个子集的第一个元素中获取列表：

k = ((12,12.356,40.365),(458,12.2258,42.69))
result = [t[0] for t in k]
print(result)

结果：

[12, 458]