Here is my dataset:

```
Unique_ID   No_of_Filings   Req_1   Req_2   Req_3   Req_4
 RCONF045   3               Blue    Red     White   Violet
 RCONF046   3               Blue    Red     White   Brown
 RCONF047   3               Blue    Red     White   Brown
 RCONF048   3               Black   Yellow  Green   N/A
 RCONF051   4               Black   Yellow  Green   N/A
 RCONF052   4               Black   Brown   Green   Orange

```

I've extracted the **unique** values from the last 4 columns (Req\_1 through Req\_4) by the following:

```
pd.unique(df1[["Req_1","Req_2","Req_3","Req_4"]].values.ravel("K"))

Out[20]:  array(['Blue', 'Black', 'Red', 'Yellow', 'Brown', 'White', 'Green',
       'Violet', nan, 'Orange'], dtype=object)

```

Here's what I need for the output. Frequency = how many times it shows up in the last four columns (e.g. Yellow only shows up twice) and Number of Filings = sum(No\_of\_Filings **if the requirement is in that row**). For example, Blue is in the first three rows, so that's 3 + 3 + 3 = 9 and Brown is in the second, third, and sixth row, so it's 3 + 3 + 4 = 10

```
Requirements    Frequency   Number of Filings
   Blue            3              9
   Black           3              11
   Red             3              9
   Brown           3              10
   White           3              9
   Green           3              11
   Yellow          2              7
   N/A             2              7
   Violet          1              3
   Orange          1              4

```

How can I create those two columns in my newly-created dataframe above using pandas? 

Thanks