Top "Data.table" questions

The R data.

Extract a column from a data.table as a vector, by position

How do I extract a column from a data.table as a vector by its position? Below are some code …

r vector indexing data.table
How to select R data.table rows based on substring match (a la SQL like)

I have a data.table with a character column, and want to select only those rows that contain a substring …

r data.table string-matching
What does .SD stand for in data.table in R

.SD looks useful but I do not really know what I am doing with it. What does it stand for? …

r data.table
Convert a data frame to a data.table without copy

I have a large data frame (in the order of several GB) that I'd like to convert to a data.…

r dataframe reference data.table
best way to transpose data.table

[UPDATE: there is now a native transpose() function in data.table package] I often need to transpose a data.table, …

r data.table
Summarizing multiple columns with data.table

I'm trying to use data.table to speed up processing of a large data.frame (300k x 60) made of several …

r data.table
Subsetting data.table set by date range in R

I have a large dataset in data.table that I'd like to subset by a date range. My data set …

r data.table subset date-range slice
What is the practical difference between data.frame and data.table in R

Apparently in my last question I demonstrated confusion between data.frame and data.table. Admittedly, I didn't realize there was …

r data.table
Rounding selected columns of data.table in R

I have following data and code to round selected columns of this data.table: > dput(mydf) structure(list(vnum1 = …

r data.table
How to select columns in data.table using a character vector of certain column names?

I am trying to select those columns in a data.table whose name appears in my character vector. The operation …

r data.table