如何解决pandas中多列的断言错误 [英] How to resolve Assertion Error for multiple columns in pandas

问题描述

Pandas文档提供了以下代码，效果很好:

Pandas documentation has given following code, which works fine:

 frame = pd.DataFrame(np.arange(12).reshape((4, 3)),
     index=[['a', 'a', 'b', 'b'], [1, 2, 1, 2]],
     columns=[['Ohio', 'Ohio', 'Colorado'],
     ['Green', 'Red', 'Green']])

基于上述概念，我尝试了以下代码，但它不起作用:

I tried following code, based on above concept, but it does not work:

hi5 = pd.DataFrame([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], 
    index = [['a','a','a','b'],[1,2,3,1]], 
    columns=[['Ohio', 'Ohio', 'Colorado'], 
    ['Green', 'Red', 'Green']])

上面的代码给出以下错误:

It is giving Following error for above code:

AssertionError: 2 columns passed, passed data had 3 columns

推荐答案

我认为它更深入:

以下代码有效:

frame = pd.DataFrame(np.array([[ 0,  1,  2], [ 3,  4,  5], [ 6,  7,  8], [ 9, 10, 11]]),
index=[['a', 'a', 'a', 'b'], [1, 2, 3, 1]],
columns=[['Ohio', 'Ohio', 'Colorado'],
['Green', 'Red', 'Green']])

下面的代码不起作用，唯一的区别是我们现在传递的是列表而不是数组:

The code below doesn't work, the only difference is we're now passing a list instead of an array:

frame = pd.DataFrame([[ 0,  1,  2], [ 3,  4,  5], [ 6,  7,  8], [ 9, 10, 11]],
index=[['a', 'a', 'a', 'b'], [1, 2, 3, 1]],
columns=[['Ohio', 'Ohio', 'Colorado'],
['Green', 'Red', 'Green']])

AssertionError: 2 columns passed, passed data had 3 columns

但是，如果我们将此代码分成多个步骤，它将再次起作用.

However, if we split this code up into steps, it works again.

frame = pd.DataFrame([[ 0,  1,  2], [ 3,  4,  5], [ 6,  7,  8], [ 9, 10, 11]])
frame.index=[['a', 'a', 'a', 'b'], [1, 2, 3, 1]]
frame.columns=[['Ohio', 'Ohio', 'Colorado'],
['Green', 'Red', 'Green']]

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