Alice Wines wrote:
>
> Hello all,
>
> I have a quandry I have been scratching my head about for a
> while. I've searched the manual and the web and have not been able to
> find an acceptable result, so I am hoping for some help.
>
> I have two data frames and I want to index into the first using
> the second, and replace the specific values I have indexed with more
> values from the second data.frame. I can do this using a loop, but I
> wanted a quicker solution with no loops involved.
>
> Although my data set is much larger than this, a small example of what
> I am trying to do is as follows:
>
> df1 <- data.frame(rows=c("A","B","C", "B", "C", "A"),
> columns=c("21_2", "22_2", "23_2", "21_2", "22_2", "23_2"),
> values=c(3.3, 2.5, 67.2, 44.3, 53, 66))
> df2 <- data.frame(matrix(rep(NA, length(df1$values)),nrow=3, ncol=3))
> names(df2) <- c("21_2", "22_2", "23_2")
> row.names(df2) <- c("A", "B", "C")
>
>> df1
> rows columns values
> 1 A 21_2 3.3
> 2 B 22_2 2.5
> 3 C 23_2 67.2
> 4 B 21_2 44.3
> 5 C 22_2 53.0
> 6 A 23_2 66.0
>
> .......
>
> What I want to see is the following:
>
>>df3
> 21_2 22_2 23_2
> A 3.3 NA 66.0
> B 44.3 2.5 NA
> C NA 53.0 67.2
>
How about this (I have converted df2 into a matrix)
df2 <- matrix(rep(NA, length(df1$values)),nrow=3, ncol=3)
colnames(df2) <- c("21_2", "22_2", "23_2")
rownames(df2) <- c("A", "B", "C")
df2[cbind(df1$rows,df1$columns)] <- df1$values
# convert df2 to a data.frame
Berend--
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