I have a lot of categorical columns and want to convert values in those columns to numerical values so that I will be able to apply ML model.

Now by data looks something like below.

Column 1- Good/bad/poor/not reported column 2- Red/amber/green column 3- 1/2/3 column 4- Yes/No

Now I have already assigned numerical values of 1,2,3,4 to good, bad, poor, not reported in column 1 .

So, now can I give the same numerical values like 1,2,3 to red,green, amber etc in column 2 and in a similar fashion to other columns or will doing that confuse model when I implement it

CodePudding user response：

The colour values you mention are nominal. There is no ranking or order to these values. If you assign 1,2,3 etc the data can be misrepresented as being from a scale.

To avoid this you can transform them by using the onehotencoder technique. This effectively encodes a multi value categorical field into the following:

red = 100
amber = 010
green = 001

You can use the following library from sk-learn.preprocessing: https://scikit-learn.org/stable/modules/generated/sklearn.preprocessing.OneHotEncoder.html