Arun

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Arun has asked 18 questions and find answers to 633 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

R merge a particular column from one data frame to another according to its reference column
data.table confusion using rollends argument of rolling join
"dims [product 0] do not match the length of object" error in R when using daply for frequency counts
Optimal way in data.table to make multiple columns from vectors of column name strings
Transactions reshaping from long to wide, joining Buy and Sell dataframes
How to create a python-style dictionary by data.table in R?
Subtraction within Groups using R
Add a column to dataframe from values of next row
Change row values to zero if less than row standard deviation
creating a data.frame whose column will hold a list in each row [duplicate]