Calculate mean of column for each row excluding the row for which mean is calculated
you can dataframe["ColumnName"].mean() for single column, or dataframe.describe() for all columns
I need to calculate the mean of a certain column in DataFrame, so that means for each row is calculated excluding the value of the row for which it's calculated. 
I know I can iterate each row by index, dropping each row by index in every iteration, and then calculating mean. I wonder if there's a more efficient way of doing it.