George Shimanovsky questions

George Shimanovsky answers

• Calculate relative RMSE in r
• Keyed lookup on data.table without 'with'
• Select columns based on multiple attribute conditions
• Python pandas cumsum with reset everytime there is a 0
• convert string date to R Date FAST for all dates
• Subsetting data.table using variables with same name as column
• Thousand separator in label of x or y axis
• Find out the number of days of a month in R