Filter by ranges supplied by two vectors, without a join operation

问题

I wish to do exactly this: Take dates from one dataframe and filter data in another dataframe - R

except without joining, as I am afraid that after I join my data the result will be too big to fit in memory, prior to the filter.

Here is sample data:

tmp_df <- data.frame(a = 1:10)

I wish to do an operation that looks like this:

lower_bound <- c(2, 4)
upper_bound <- c(2, 5)
tmp_df %>%
    filter(a >= lower_bound & a <= upper_bound) # does not work as <= is vectorised inappropriately

and my desired result is:

> tmp_df[(tmp_df$a <= 2 & tmp_df$a >= 2) | (tmp_df$a <= 5 & tmp_df$a >= 4), , drop = F] 
# one way to get indices to subset data frame, impractical for a long range vector
  a
2 2
4 4
5 5

My problem with memory requirements (with respect to the join solution linked) is when tmp_df has many more rows and the lower_bound and upper_bound vectors have many more entries. A dplyr solution, or a solution that can be part of pipe is preferred.

回答1:

Maybe you could borrow the inrange function from data.table, which

checks whether each value in x is in between any of the intervals provided in lower,upper.

Usage:

inrange(x, lower, upper, incbounds=TRUE)

library(dplyr); library(data.table)

tmp_df %>% filter(inrange(a, c(2,4), c(2,5)))
#  a
#1 2
#2 4
#3 5

回答2:

If you'd like to stick with dplyr it has similar functionality provided through the between function.

# ranges I want to check between
my_ranges <- list(c(2,2), c(4,5), c(6,7))

tmp_df <- data.frame(a=1:10)
tmp_df %>% 
  filter(apply(bind_rows(lapply(my_ranges, 
                                FUN=function(x, a){
                                  data.frame(t(between(a, x[1], x[2])))
                                  }, a)
                         ), 2, any))
  a
1 2
2 4
3 5
4 6
5 7

Just be aware that the argument boundaries are included by default and that cannot be changed as with inrange

来源：https://stackoverflow.com/questions/44621700/filter-by-ranges-supplied-by-two-vectors-without-a-join-operation

标签

data.table

dplyr

subset