On Dec 7, 2010, at 11:30 AM, Pete Pete wrote:


Hi,
consider the following two dataframes:
x1=c("232","3454","3455","342","13")
x2=c("1","1","1","0","0")
data1=data.frame(x1,x2)

y1=c("232","232","3454","3454","3455","342","13","13","13","13")
y2=c("E1","F3","F5","E1","E2","H4","F8","G3","E1","H2")
data2=data.frame(y1,y2)

I need a new column in dataframe data1 (x3), which is either 0 or 1
depending if the value "E1" in y2 of data2 is true while x1=y1. The result
of data1 should look like this:
  x1     x2 x3
1 232   1   1
2 3454 1   1
3 3455 1   0
4 342   0   0
5 13     0   1

I think a SQL command could help me but I am too inexperienced with it to
get there.

> dat3 <- merge(data1, data2[data2$y2=="E1", ], by.x="x1", by.y="y1", all.x=TRUE)
> dat3$y2 <- 0 + (dat3$y2 %in% "E1")
> dat3
    x1 x2 y2
1   13  0  1
2  232  1  1
3  342  0  0
4 3454  1  1
5 3455  1  0

(Admittedly not in the original order, but in my hands the R merge operation doesn't lend itself well to maintaining the original order. I see that Grothendieck's solution is better in this respect, a typical occurrence in comparison of our respective efforts with R.)

--

David Winsemius, MD
West Hartford, CT

______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Reply via email to