Frank

Frank has asked 20 questions and find answers to 507 problems.

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Frank questions

using return list macros with `: list' syntax
fill rows downward for a column with NAs (with R base or data.table)
splitting (1:n)[boolean] into contiguous sequences
accessing Y columns with duplicated names in j of X[Y, j] merges
print the data.table package's .onAttach messages with knitr
Clean, simple function factories in R
Using data.table's .() shortcut in quoted expressions
lapply-ing with the "$" function
Efficiently computing a linear combination of data.table columns
data.table `:=` assignment expressions with dynamic inputs (existing columns) and outputs (new column names)

Frank answers

Vectorize loop with repeating indices
Random binary matrix with row and column sum constraints
Fill missing dates with previous value by group
Calculate number of singletons in R
How to melt by all combination pairs of a column?
Pass data.table column into function when using .SDcols
Cumulative sum base on the value of different columns in the same row of a dataframe (avoiding loops)
How can we do some calculations using last row within a group in data.table in R?
replace every other space with new line
Calculating overlap (and distance measures) for categorical variables in R