[R] Dataframe modification

Gabor Grothendieck ggrothendieck at gmail.com
Mon Aug 21 20:49:12 CEST 2006

```I think the first one still works in that case.
If reordering the rows is ok then the second one works too.

A <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2, 3, 4, 5, 6, 7,8,9,10,11,12)
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
DF

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

On 8/21/06, Sachin J <sachinj.2006 at yahoo.com> wrote:
>
> Hi Gabor,
>
> Thanx for the help. I forgot to mention this. Column A is something like
> this
>
> A <- c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1, 2, 3, 4, 5, 6,
> 7,8,9,10,11,12)
>
> i.e it repeats. Rest all is same. How can I modify your solution to take
> care of this issue.
>
>
> Sachin
>
>
>
> Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
>
> 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 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
> >
> > __________________________________________________
> >
> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> >
>
>
>
>
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```