View(subset) leading to internal error

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
30/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
r
Domain
data-engineering

Research direction

Reproduce the supplied data.table and dplyr example, especially the final View(w[c1=="a",]) call. Start at R/setkey.R around getindex, which the report identifies as the traceback location. Done means the example no longer produces the internal invalid-index error, including when rerun in terminal R and RStudio.

Written by the indexing model from the issue text.

Description

not reproducible

As reported on SO:

https://stackoverflow.com/questions/57348423/data-table-and-dplyr-compatibility

library(data.table)
library(dplyr)


x1 = data.table(c1 = c("a", "a", "a", "a", "b", "b", "c"),
                c2 = c("x", "y", "x", "z", "y", "x", "x"),
                c3 = c(1, 3, 5, 2, 2, 7, 9))
x2 = data.table(c1 = c("a", "a", "a", "a", "b", "b", "c"),
                c2 = c("x", "y", "x", "z", "y", "x", "x"),
                c3 = c(1, 3, 5, 2, 2, 7, 9)) 

xx = rbind(x1, x2)

w = xx %>%
  select (c1, c2, c3) %>%
  group_by(c1,c2)  %>%
  summarise(c4 = mean(c3))  %>%
  ungroup() %>%
  setDT()

View(w[c1=="a",])

Error in View : Internal error: index 'c1' exists but is invalid

Traced back to getindex here:

https://github.com/Rdatatable/data.table/blob/master/R/setkey.R#L133

I was able to reproduce this, though now after playing around with it for about 10 minutes.... the problem went away! Both in terminal R and in RStudio...

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