Graphics Reference
In-Depth Information
See Also
See
Converting Data from Long to Wide
to do conversions in the other direction, from long to
wide.
See the
stack()
function for another way of converting from wide to long.
Converting Data from Long to Wide
Problem
You want to convert a data frame from “long” format to “wide” format.
Solution
Use the
dcast()
function from the
reshape2
package. In this example, we'll use the
plum
data
set, which is in a long format:
library(gcookbook)
# For the data set
plum
length time survival count
long at_once dead
84
long in_spring dead
156
short at_once dead
133
short in_spring dead
209
long at_once alive
156
long in_spring alive
84
short at_once alive
107
short in_spring alive
31
The conversion to wide format takes each unique value in one column and uses those values
as headers for new columns, then uses another column for source values. For example, we can
“move” values in the
survival
column to the top and fill them with values from
count
:
library(reshape2)
dcast(plum, length
+
time ~ survival, value.var
=
"count"
)
length time dead alive
long at_once
84
156
long in_spring
156
84
short at_once
133
107
short in_spring
209
31
