alexis_laz questions

alexis_laz answers

• R: count how many letters match from beginning of string
• Add a column of derived data to a data.frame
• R data.table apply function to all pair of columns
• capture column pattern frequency
• find column value and name based on minimum value in other column
• Creating a R data frame in C/C++
• Reduce a nested list with varying length
• Fill NA in a time series only to a limited number
• How to assign "cut" range midpoints in R?
• Big matrix and memory problems