aggregate.data.frame(x, by, FUN, ...)
x
is not a data frame, it is converted to one using the
data.frame
function.
x
. The list elements should be named so that the result can use those names for its corresponding columns.
x
and that returns a single value.
FUN
.
by
and
x
. The columns arising from
by
contain each unique combination of values in the grouping vectors (excluding combinations not seen in the data). These columns have data class
"factor"
. The columns arising from
x
contain the value of
FUN
applied to the partitions induced by the grouping vectors on each column of
x
.
This is the
"data.frame"
method for the generic function
aggregate
.
If
x
has columns of various types, it might be difficult to find a summary function that works on all columns. Instead, it may be easier to use
aggregate.data.frame
on only certain columns of
x
.
aggregate(fuel.frame[,1:4], list(Type=fuel.frame$Type), mean) # Produces: # Type Weight Disp. Mileage Fuel # Compact Compact 2821.000 140.40000 24.13333 4.167655 # Large Large 3676.667 279.33333 20.33333 4.967794 # Medium Medium 3195.769 175.84615 21.76923 4.601413 # Small Small 2257.692 97.30769 31.00000 3.273380 # Sporty Sporty 2798.889 164.11111 26.00000 3.957606 # Van Van 3517.143 164.42857 18.85714 5.313283