Create Hex column from Red column, Green column & Blue column in pandas

Question

I have a pandas data frame with 16,777,216 rows. This is every possible combination of three columns (Red, Green and Blue) between 0 and 255 inclusive.

I would like to add a column to this data frame which is the hex code of the three values of the row. I thought something like the below would have been the best solution:

df["Hex"] = "#{0:02x}{1:02x}{2:02x}".format(df["Red"],df["Green"],df["Blue"])

However, it appears you can't pass a series into the string format method.

Is there a way of getting around this problem? Furthermore, would that be the most efficient way of doing it, given the data frame is fairly large?

Answer 1

You can use .apply, eg:

df = pd.DataFrame(np.random.randint(256, size=(10, 3)), columns=['Red', 'Green', 'Blue'])

eg:

   Red  Green  Blue
0  125    100   174
1  107    247   235
2  230    254    33
3   91    107    33
4  209    220   232
5  175     10    47
6  120     66    44
7   21    136   254
8  226    237    32
9   89     57    71

Then:

df.apply('#{Red:02X}{Green:02X}{Blue:02X}'.format_map, axis=1)

Gives you:

0    #7D64AE
1    #6BF7EB
2    #E6FE21
3    #5B6B21
4    #D1DCE8
5    #AF0A2F
6    #78422C
7    #1588FE
8    #E2ED20
9    #593947
dtype: object