Compute summary statistics for subsets of a hyperSpec
object.
hyperSpec
object.
grouping for the rows of x@data
.
Either a list containing an index vector for each of the subgroups
or a vector that can be split
in such a list.
function to compute the summary statistics
further arguments passed to FUN
number of rows in the resulting hyperSpec
object,
for memory pre-allocation.
If more rows are needed, how many should be appended?
Defaults to 100 or an estimate based on the percentage of groups that
are still to be done, whatever is larger.
If a list is given in by
: does the list already
contain the row indices of the groups? If FALSE
, the list in
by
is computed first (as in stats::aggregate()
).
A hyperSpec
object with an additional column @data$.aggregate
tracing which group the rows belong to.
aggregate()
applies FUN
to each of the subgroups given by by
.
It combines the functionality of stats::aggregate()
, base::tapply()
,
and stats::ave()
for hyperSpec
objects.
aggregate()
avoids splitting x@data
.
FUN
does not need to return exactly one value. The number of
returned values needs to be the same for all wavelengths (otherwise the
result could not be a matrix), see the examples.
If the initially pre-allocated data.frame
turns out to be too small,
more rows are appended and a warning is issued.
region.means <- aggregate(faux_cell, faux_cell$region, mean_pm_sd)
plot(region.means,
stacked = ".aggregate", fill = ".aggregate",
col = palette_matlab_dark(3)
)
## make some "spectra"
spc <- new(
"hyperSpec",
spc = sweep(matrix(rnorm(10 * 20), ncol = 20), 1, (1:10) * 5, "+")
)
## 3 groups
color <- c("red", "blue", "black")
by <- as.factor(c(1, 1, 1, 1, 1, 1, 5, 1, 2, 2))
by
#> [1] 1 1 1 1 1 1 5 1 2 2
#> Levels: 1 2 5
plot(spc, "spc", col = color[by])
## Example 1: plot the mean of the groups
plot(aggregate(spc, by, mean), "spc",
col = color, add = TRUE,
lines.args = list(lwd = 3, lty = 2)
)
## Example 2: FUN may return more than one value (here: 3)
plot(aggregate(spc, by, mean_pm_sd), "spc",
col = rep(color, each = 3), lines.args = list(lwd = 3, lty = 2)
)
## Example 3: aggregate even takes FUN that return different numbers of
## values for different groups
plot(spc, "spc", col = color[by])
weird.function <- function(x) {
if (length(x) == 1) {
x + 1:10
} else if (length(x) == 2) {
NULL
} else {
x[1]
}
}
agg <- aggregate(spc, by, weird.function)
#> Warning: At3of3levels: Output data.frame too small. Consider using anappropriate value for out.rows to speed up calculations.
agg$.aggregate
#> [1] 1 5 5 5 5 5 5 5 5 5 5
#> Levels: 1 2 5
plot(agg, "spc",
add = TRUE, col = color[agg$.aggregate],
lines.args = list(lwd = 3, lty = 2)
)