This function returns a dataframe with feature names and their frequency ratio, percentage of the unique value and logic values indicating whether the feature is zero variance or has near zero variance.
feature : name of the features.
flag.zv (Flag Zero Variance) : True/False, flagging zero variance.
fr (Frequency Ratio) : the ratio of the value with the highest frequency over the value with the second highest frequency.
puv (Percentage of Unique Values) : number of the unique values divided by the total number of samples.
flag.nzv (Flag Near Zero Variance) : True/False, flagging near zero variance.