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How can I subset a table based on values and return those values? This returns just indices:
with(chickwts, table(feed))
with(chickwts, table(feed)) > 11
which(with(chickwts, table(feed)) > 11)
Output
> with(chickwts, table(feed))
feed
casein horsebean linseed meatmeal soybean sunflower
12 10 12 11 14 12
> with(chickwts, table(feed)) > 11
feed
casein horsebean linseed meatmeal soybean sunflower
TRUE FALSE TRUE FALSE TRUE TRUE
> which(with(chickwts, table(feed)) > 11)
casein linseed soybean sunflower
1 3 5 6
291
Method 2: Subsetting in R Using [[ ]] Operator [[ ]] operator is used for subsetting of list-objects. This operator is the same as [ ] operator but the only difference is that [[ ]] selects only one element whereas [ ] operator can select more than 1 element in a single command.
The most general way to subset a data frame by rows and/or columns is the base R Extract[] function, indicated by matched square brackets instead of the usual matched parentheses. For a data frame named d the general format is d[rows, columms] .
By using bracket notation on R DataFrame (data.name) we can select rows by column value, by index, by name, by condition e.t.c. You can also use the R base function subset() to get the same results. Besides these, R also provides another function dplyr::filter() to get the rows from the DataFrame.
You need to use the computed value twice, so its useful to use an intermediate variable:
x <- with(chickwts, table(feed))
x[x>11]
feed
casein linseed soybean sunflower
12 12 14 12
Here is an other approach making use of the Filter function:
Filter(function(x) x > 11, with(chickwts, table(feed)))
feed
casein linseed soybean sunflower
12 12 14 12
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