Dataframe modification

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

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.

Thanx in advance.

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