# [R] Dataframe modification

Gabor Grothendieck ggrothendieck at gmail.com
Mon Aug 21 20:31:04 CEST 2006

Here are two solutions:

A <- 1:8
B <- c(1,2,4,7,8)
C <- c(5,3,10,12,17)

# solution 1 - assignment with subscripting
DF <- data.frame(A, B = A, C = 0)
DF[A %in% B, "C"] <- C

# solution 2 - merge
DF <- with(merge(data.frame(A), data.frame(B, C), by = 1, all = TRUE),
data.frame(A, B = A, C = ifelse(is.na(C), 0, C)))

On 8/21/06, Sachin J <sachinj.2006 at yahoo.com> wrote:
> Hi,
>
>  How can I accomplish this in R.
>
>  I have a Dataframe with 3 columns. Column B and C have same elements. But column A has more elements than B and C. I want to compare Column A with B and do the following:
>
>  If A is not in B then insert a new row in B and C and fill these new rows with
>  B = A and C = 0. So finally I will have balanced dataframe with equal no of rows (entries) in all the columns.
>
>  For example:
>
>  A[3] = 3 but is not in B. So insert new row  and set B[3]  = 3 (new row) and C[3] = 0. Final result would look like:
>
>  A   B   C
>  1    1    5
>  2    2    3
>  3    3    0
>  4    4   10
>  5    5    0
>  6    6    0
>  7    7    12
>  8    8    17
>
>  These are the columns of DF
>  > a <- c(1,2,3,4,5,6,7,8)
>  > b <- c(1,2,4,7,8)
>  > c(5,3,10,12,17)
>
>  Thanx in advance for the help.
>
>  Sachin
>
>  __________________________________________________
>
>
>
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>
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