Merging Data Frames
In the relational database world, one of the most important operations is that of a join, in which two tables can be combined according to the values of a common variable. In R, two data frames can be similarly combined using the merge()
function.
The simplest form is as follows:
merge(x,y)
This merges data frames x
and y
. It assumes that the two data frames have one or more columns with names in common. Here’s an example:
> d1 kids states 1 Jack CA 2 Jill MA 3 Jillian MA 4 John HI > d2 ages kids 1 10 Jill 2 7 Lillian 3 12 Jack > d <- merge(d1,d2) > d kids states ages 1 Jack CA 12 2 Jill MA 10
Here, the two data frames have the variable kids
in common. R found the rows in which this variable had the same value of kids
in both ...
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