pandas pivot_table，按列对值排序 [英] Pandas pivot_table, sort values by columns

问题描述

我是Pandas的新用户，我喜欢它！

I am a new user to Pandas and I love it!

我正在尝试在Pandas中创建数据透视表.有了所需的数据透视表后，我想按列对值进行排名.

I am trying to create a pivot table in Pandas. Once I have pivot table the way I want, I would like to rank the values by the columns.

我已附加了Excel中的图像，因为以表格格式更容易看到我要实现的目标.链接到图像

I've attached an image from Excel as it is easier to see in tabular format what I am trying to achieve. Link to image

我已经搜索了stackoverflow，但是找不到答案.我尝试使用.sort()，但这不起作用.任何帮助将不胜感激.

I've searched through stackoverflow but am having trouble finding an answer. I tried using .sort() but this doesn't work. Any help will be appreciated.

预先感谢

推荐答案

这应该可以满足您的需求:

This should do what you are looking for:

In [1]: df = pd.DataFrame.from_dict([{'Country': 'A', 'Year':2012, 'Value': 20, 'Volume': 1}, {'Country': 'B', 'Year':2012, 'Value': 100, 'Volume': 2}, {'Country': 'C', 'Year':2013, 'Value': 40, 'Volume': 4}])

In [2]: df_pivot = pd.pivot_table(df, index=['Country'], columns = ['Year'],values=['Value'], fill_value=0)

In [3]: df_pivot
Out [4]:
    Value     
Year     2012 2013
Country           
A          20    0
B         100    0
C           0   40

In [5]: df = df_pivot.reindex(df_pivot['Value'].sort_values(by=2012, ascending=False).index)

Out [6]: 
    Value     
Year     2012 2013
Country           
B         100    0
A          20    0
C           0   40

基本上，它获取排序后的值的索引并为初始数据透视表重新索引.

Basically it gets the index of the sorted values and reindex the initial pivot table.

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