沿短轴延伸 pandas 面板框架 [英] Extending a pandas panel frame along the minor axis

问题描述

我想沿熊猫的短轴扩展Panel数据框.我开始创建dic的dic来生成面板.

I would like to extend a Panel frame of data along a minor axis in pandas. I start off creating a dic of DataFrames to generate a Panel.

import pandas as pd
import numpy as np
rng = pd.date_range('1/1/2013',periods=100,freq='D')
df1 = pd.DataFrame(np.random.randn(100, 4), index = rng, columns = ['A','B','C','D'])
df2 = pd.DataFrame(np.random.randn(100, 4), index = rng, columns = ['A','B','C','D'])
df3 = pd.DataFrame(np.random.randn(100, 4), index = rng, columns = ['A','B','C','D'])
pf = pd.Panel({'df1':df1,'df2':df2,'df3':df3})

正如我所料，发现我有一个具有以下尺寸的面板:

As expected I, find I have a panel with the following dimensions:

尺寸:3(项)x 100(长轴)x 4(小轴)项目轴: df1至df3长轴轴:2013-01-01 00:00:00至2013-04-10 00:00:00 次轴:A到D

Dimensions: 3 (items) x 100 (major_axis) x 4 (minor_axis) Items axis: df1 to df3 Major_axis axis: 2013-01-01 00:00:00 to 2013-04-10 00:00:00 Minor_axis axis: A to D

我现在想向Minor轴添加一个新的数据集:

I would now like to add a new data set to the Minor axis:

pf['df1']['E'] = pd.DataFrame(np.random.randn(100, 1), index = rng)
pf['df2']['E'] = pd.DataFrame(np.random.randn(100, 1), index = rng)
pf['df2']['E'] = pd.DataFrame(np.random.randn(100, 1), index = rng)

我发现添加此新的短轴后，面板数组尺寸的形状没有改变:

I find that after adding this new minor axis the shape of the panel array dimensions has not changed:

shape(pf)

[3,100,4]

[3,100,4]

我能够访问major_axis中每个项目的数据:

I am able to access the data for each of the items in the major_axis:

pf.ix['df1',-10:,'E']

2013-04-01 0.168205 2013-04-02 0.677929 2013-04-03 0.845444 2013-04-04 0.431610 2013-04-05 0.501003 2013-04-06 -0.403605 2013-04-07 -0.185033 2013-04-08 0.270093 2013-04-09 1.569180 2013-04-10 -1.374779频率:D，名称:E

2013-04-01 0.168205 2013-04-02 0.677929 2013-04-03 0.845444 2013-04-04 0.431610 2013-04-05 0.501003 2013-04-06 -0.403605 2013-04-07 -0.185033 2013-04-08 0.270093 2013-04-09 1.569180 2013-04-10 -1.374779 Freq: D, Name: E

但是如果我将切片扩展为包括多个主轴，则

But if I extend the slicing to include more than one major axis:

pf.ix[:,:,'E']

然后我遇到一个错误，说'E'是未知的.

Then I encounter an error saying that 'E' is unknown.

任何人都可以建议我要去哪里哪里或执行此操作的更好方法吗?

Can anyone suggest where I am going wrong or a better way of performing this operation?

推荐答案

现在不起作用， https://github.com/pydata/pandas/issues/2578 但是您可以通过这种方式完成您想要的工作.这是很便宜的操作，因为什么也没有 复制.

This doesn't work right now see this, https://github.com/pydata/pandas/issues/2578 But you can accomplish what you want this way. This is a pretty cheap operation as nothing is copied.

In [18]: x = pf.transpose(2,0,1)

In [19]: x
Out[19]: 
<class 'pandas.core.panel.Panel'>
Dimensions: 4 (items) x 3 (major_axis) x 100 (minor_axis)
Items axis: A to D
Major_axis axis: df1 to df3
Minor_axis axis: 2013-01-01 00:00:00 to 2013-04-10 00:00:00

In [20]: x['E'] = new_df

In [21]: x.transpose(1,2,0)
Out[21]: 
<class 'pandas.core.panel.Panel'>
Dimensions: 3 (items) x 100 (major_axis) x 5 (minor_axis)
Items axis: df1 to df3
Major_axis axis: 2013-01-01 00:00:00 to 2013-04-10 00:00:00
Minor_axis axis: A to E

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