I think using the base::merge function is not needed, as using data.table joins can be a lot faster. E.g. see the following. I make x and y data.tables with 3-3 columns:. Posts about merge data table in R written by rhandbook. The example I present here is a little silly, yet it illustrates how to join tables with data.table in R. Mapping old data to new dataCategories in general are never fixed, they always change at some point.
We can get order log(N) scaling though with join option of data.table. If you need to speed things up, give data.table a try. This is a post about data.table, a popular package for summarizing data in R. 2014.12, JOINing data in R using data.table, Ronald Stalder.
The R data.table package is rapidly making its name as the number one choice for handling large datasets in R. The course finishes with more complex concepts such as indexing, keys and fast ordered joins. Furthermore i may itself be a data.table which invokes a fast table join using binary search in O(log n). The three most commonly used functions for joins are merge in base R, join in plyr and the merging functionality in data.table. Each has pros and cons with some pros outweighing their respective cons.
Elegant & Fast Data Manipulation With
Then, we can merge the two data.frame objects, sort by the sequence, and delete the sequence. Questions and discussion about the data.table package in R. The package extends data.frame to provide keys, fast grouping, fast extract and fast joins in a short and flexible syntax. In a perfect data world the tables you need to join have common IDs. In this setting, in R, you might use the merge function from the base package or the speedy and useful join functions from the d. Data.table expert. Selecting rows the data.table way; Understanding automatic indexing; Selecting groups or parts of groups; Rolling joins. The data that you need for a report could be located in more than one table. In order to select the data from the tables, join the tables in a query. Joining tables enables you to select data from multiple tables as if the data were contained in one table.