Frank

Frank has asked 19 questions and find answers to 464 problems.

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"I mean, a horse is a horse of course, but who rides is important."

Frank questions

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)
Saving plots in a data.table list column

Frank answers

creating new variable that takes into account prior information from the earlier records
Cbind two data but with some modifications using data.table
Creating canonical basis vectors in R?
How to dynamically use lapply in data.table?
Conditional keyed join/update _and_ update a flag column for matches
How can I reshape my data.table efficiently
Finding rows of a large matrix that match specific values
Strange error when expanding data.table
How to create a unique list of combinations from multiple vectors?
Create a new factor/variable with levels based on "N" consecutive occurrences of original factor level