Frank

Frank has asked 20 questions and find answers to 508 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

Sub-indexing a list to apply a function in R
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