New posts in Plyr

Create an "index" for each element of a group with data.table

Reshape multiple categorical variables to binary response variables

Why am I seeing "Error: length(rows) == 1 is not TRUE" with ddply?

Compute rolling sum by id variables, with missing timepoints

Count occurrences of factor in R, with zero counts reported

Aggregate a data frame based on unordered pairs of columns

Calculate proportions within subsets of a data frame

Efficient multiplication of columns in a data frame

Block bootstrap from subject list

Getting at the previous n-rows in a data frame?