Reshape a data frame from long form to wide form
longToWide(data, formula, sep = "_")The data frame.
A two-sided formula specifying measure variables and within-subject variables
Separator string used in wide-form variable names
The output is a "wide form" data frame in containing one row per
subject (or experimental unit, more generally), with each observation of
that subject corresponding to a separate variable. The naming scheme for
these variables places the name of the measured variable first, followed
by the levels of within-subjects variable(s), separated by the separator
string sep. In the example above where the reshaping formula was
accuracy ~ time, if the default separator of sep="_" was
used, and the levels of the time variable are t1, t2and t3, then the output would include the variables
accuracy_t1, accuracy_t2 and accuracy_t3.
In the second example listed above, where the reshaping formula was
rt + accuracy ~ days + sessions, the output variables would refer
to levels of both within-subjects variables. For instance,
rt_day1_session1, and accuracy_day2_session1 might be the
names of two of the variables in the wide form data frame.
The longToWide function is the companion function to
wideToLong. The data argument is a "long form" data frame,
in which each row corresponds to a single observation. The output is a
"wide form" data frame, in which each row corresponds to a single
experimental unit (e.g., a single subject).
The reshaping formula should list all of the measure variables on the
left hand side, and all of the within-subject variables on the right
hand side. All other variables are assumed to be between-subject variables.
For example, if the accuracy of a participant's performance is
measured at multiple time points, then the formula would be
accuracy ~ time.
Multiple variables are supported on both sides of the formula. For example,
suppose we measured the response time rt and accuracy of
participants, across three separate days, and across three separate
sessions within each day. In this case the formula would be
rt + accuracy ~ days + sessions.
long <- data.frame(
id = c(1, 2, 3, 1, 2, 3, 1, 2, 3),
time = c("t1", "t1", "t1", "t2", "t2", "t2", "t3", "t3", "t3"),
accuracy = c(.50, .03, .72, .94, .63, .49, .78, .71, .16)
)
longToWide(long, accuracy ~ time)
#> id accuracy_t1 accuracy_t2 accuracy_t3
#> 1 1 0.50 0.94 0.78
#> 2 2 0.03 0.63 0.71
#> 3 3 0.72 0.49 0.16