I have a simple question, to which I have not been able to find a solution here:
When I want to keep a selection of variables from a data frame, the variables get removed from all copies of that data frame loaded in my workspace.
Is there a way to only remove it from a single data frame?
A reproducible example (only remove it from df and not df2)?
require(data.table)
df <- structure(list(group = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L,
2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L), x = c(0L, 0L, 0L, 1L,
1L, 1L, 1L, 0L, 0L, 0L, 0L, 0L, 0L, 1L, 1L, 1L, 0L, 1L, 1L),
time = c(1636L, 1637L, 1638L, 1639L, 1640L, 1641L, 1642L,
1683L, 1684L, 1685L, 1686L, 1687L, 1688L, 1689L, 1690L, 1691L,
1638L, 1639L, 1640L)), .Names = c("group", "x", "time"), class = "data.frame", row.names = c(NA,
-19L))
df2 <- df
varstokeep <- c("group","x")
vartodrop <- which(!names(df)%in%varstokeep)
set(df, i=NULL, j=vartodrop, value=NULL)
The reason is that I have a large file, which I use as the basis for multiple (more aggregated) files. Having to load the basic file 6 times would take a lot more time.
