用大量可能的值熊猫来融化数据框的最有效方法

Question

I have a long format dataframe like the following:

In reality, my dataframe is about 10k rows and there are about 400 possible values of category. I'd like to melt my dataframe into a wide format like the following:

I can think of a couple ways to do this, but what would be an efficient way to do this transformation?

Answer 1

这不是交叉表吗：

pd.crosstab(df['Obs'], df['Category'])

Answer 2

用crosstab检查

 out = pd.crosstab(df['Obs'], df['Category'])