Frank

Frank has asked 19 questions and find answers to 467 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

r - copy missing values from other variables
If a cell contains a certain character replace the whole cell in r
Track time in state variables in data tables in R
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