Merge / calculate difference ratios

Calculate normalized difference ratios for all possible "sur_refl" band combinations.

merge_normalized_differences(ml_df)

Arguments

ml_df

a machine learning data frame with "sur_refl" prefix column names apply the band ratios to

Value

A machine learning data frame with normalized band ratios appended

Details

This is a naive approach and a more tailored / specific methodology can use only select normalized difference band combinations by specifying which columns to consider in the lapply() routine in this function.

Additional improvements can probably be made by using purrr in some exotic combination.