Make a matrix from a data-frame-CodePudding

I have a data frame that looks like this .

I want to create a matrix where it counts the number of times each student says true and false.

How would I do this?

CodePudding user response：

Use melt and crosstab:

df2 = df.melt()
pd.crosstab(df2['variable'], df2['value'])

Output:

value     False  True
variable             
Student1      1     2
Student2      2     1
Student3      1     2

CodePudding user response：

You could stack and unstack with counting values in between:

 out = df.stack().groupby(level=1).value_counts().unstack()

But an even simpler way is to simply count values:

out = df.sum().to_frame(name='T').assign(F=lambda x: len(df) - x)

Output:

          False  True
Student1      1     2
Student2      2     1
Student3      1     2

CodePudding user response：

You can do value_counts

df.apply(pd.Series.value_counts).T
Out[205]: 
     F  T
St1  1  2
St2  2  1
St3  1  2

CodePudding user response：

You can use:

>>> df.melt().value_counts().unstack().rename_axis(index=None, columns=None)
          False  True
Student1      1     2
Student2      2     1
Student3      1     2