Arun

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Arun has asked 18 questions and find answers to 647 problems.

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Arun questions

understanding optimisation messages on assignment by reference in a data.table
When does setting 'perl=TRUE' in 'strsplit' does not work (as intended or at all)?
Warning message: in rbindlist(allargs) : NAs introduced by coercion: possible bug in data.table?
unexpected output from aggregate
Using 'mutate_' to sum a bunch of columns row-wise
Why is subsetting on a "logical" type slower than subsetting on "numeric" type?
rbindlist two data.tables where one has factor and other has character type for a column
DT[!(x == .)] and DT[x != .] treat NA in x inconsistently
Why does "^" on a data.frame return a matrix instead of a data.frame like "*" does?

Arun answers

Subset multiple columns by .N in large data.table
setDT() is not adding additional columns
How to efficiently add an order variable to a big data frame
Can data.table handle identical column names when using .SDcols?
Customize names of columns created by dcast.data.table
merge-like scenario with two data.tables
Rearrange a matrix in R using two factors
Summarize a data.table with unreliable data
Speed up vector-lookup for data.table
rbind 2 vectors of different lengths by their names