Remove constant columns with or without NAs

Question

I am trying to get many lm models work in a function and I need to automatically drop constant columns from my data.table. Thus, I want to keep only columns wit

Answer 1

For removing constant columns,

1. Numeric Columns:-

   constant_col = [const for const in df.columns if df[const].std() == 0]
   print (len(constant_col))
   print (constant_col)
   

2. Categorical Columns:-

   constant_col = [const for const in df.columns if len(df[const].unique()) == 1]
   print (len(constant_col))
   print (constant_col)
   

Then you drop the columns using the drop method