subsetting based on number of observations in a factor variable

Question

how do you subset based on the number of observations of the levels of a factor variable? I have a dataset with 1,000,000 rows and nearly 3000 levels, and I want to subset out

Answer 1

table, subset that, and match based on the names of that subset. Probably will want to droplevels thereafter.

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EIDT

Some sample data:

set.seed(1234)
data <- data.frame(factor = factor(sample(10000:12999, 1000000, 
  TRUE, prob=rexp(3000))))

Has some categories with few cases

> min(table(data$factor))
[1] 1

Remove records from case with less than 100 of those with the same value of factor.

tbl <- table(data$factor)
data <- droplevels(data[data$factor %in% names(tbl)[tbl >= 100],,drop=FALSE])

Check:

> min(table(data$factor))
[1] 100

Note that data and factor are not very good names since they are also builtin functions.