Single column with value counts from multiple column dataframe

问题

I would like to sum the frequencies over multiple columns with pandas. The amount of columns can vary between 2-15 columns. Here is an example of just 3 columns:

code1    code2    code3
27       5        56
534      27       78
27       312      55
89       312      27

And I would like to have the following result:

code    frequency
5       1
27      4
55      1
56      2
78      1
312     2
534     1

To count values inside one column is not the problem, just need a sum of all frequencies in a dataframe a value can appear, no matter the amount of columns.

回答1:

You could stack and take the value_counts on the resulting series:

df.stack().value_counts().sort_index()

5      1
27     4
55     1
56     1
78     1
89     1
312    2
534    1
dtype: int64

来源：https://stackoverflow.com/questions/61320130/single-column-with-value-counts-from-multiple-column-dataframe