[R] Conditionally remove rows with logic

[MacQueen, Don]

Assuming that within each ID the data is sorted by increasing TIME, and
that LABEL==1 occours only once within each ID. Then I would try something
like this.

Suppose that your data is in a data frame named "df".


df.keep <- logical()

for (id in unique(df$ID)) {
  df.tmp <- subset(df, df$ID==id)
  tmp.keep <- rep(TRUE, nrow(df.tmp))
  tmp.keep[df.tmp$TIME > df.tmp$TIME[df.tmp$LABEL==1]] <- FALSE
  df.keep <- c(df.keep, tmp.keep)
}

newdf <- df[df.keep , ]

I have not tested this.

I'm sure it could be made more efficient, and probably with a bit of
cleverness one could avoid creating temporary subsets of the input. But I
tend to find such subsets handy for testing and debugging.

Unless your input data is huge, it should be fast enough that you won't
notice the inefficiencies.

-Don

-- 
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





On 8/7/16, 3:21 PM, "R-help on behalf of Jennifer Sheng"
<r-help-bounces at r-project.org on behalf of jennifer.sheng2002 at gmail.com>
wrote:

>Dear all,
>
>I need to remove any rows AFTER the label becomes 1.  For example, for ID
>1, the two rows with TIME of 15 & 18 should be removed; for ID 2, any rows
>after time 6, i.e., rows of time 9-18, should be removed.  Any
>suggestions?  Thank you very much!
>
>The current dataset looks like the following:
>ID     TIME     LABEL
>1        0            0
>1        3            0
>1        6            0
>1        9            0
>1        12          1
>1        15          0
>1        18           0
>2        0            0
>2        3            0
>2        6            1
>2        9            0
>2        12          0
>2        15          0
>2        18          0
>
>Thanks a lot!
>Jennifer
>
>	[[alternative HTML version deleted]]
>
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