change value in one cell

x

x[4, "Y"] <- 0
x

Hello all,

I am wondering if there is a way to change the value of one cell in R. For
instance let's say I have a hypothetical data frame that looks like this:

Obs X Y Z
1 ? ?1 0 1
2 ? ?0 0 1
3 ? ?1 1 1
4 ? ?0 1 1
5 ? ?1 1 0
6 ? ?0 0 0

I would like to change the value of the 4th observation in the Y column from
1 to 0. It should look like this:

Obs X Y Z
1 ? ?1 0 1
2 ? ?0 0 1
3 ? ?1 1 1
4 ? ?0 0 1
5 ? ?1 1 0
6 ? ?0 0 0

Is it possible to change the value in one command?

Thanks,

Carlos


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That's great! But, I guess I should have provided a better example for
my problem. The reason being that I did not consider strings. For
instance, in my case, I'm actually trying to add a value to a data frame
that looks like this:

Obs     X
0     NA
1     "01 001"
2     "01 002"
3     "01 003"

And I am actually trying to get that specific "NA" value and convert it
to "00 000" so it can look like this:

Obs     X
0     "00 000"
1     "01 001"
2     "01 002"
3     "01 003"

When I write the code you provided, I get this result:

x[1,"X"]<-"00 000"
Warning message:
In `[<-.factor`(`*tmp*`, iseq, value = c(NA, 3L, 4L, 5L, 6L, 7L,  :

invalid factor level, NAs generated

I am wondering what I am doing wrong and how to solve this problem.

Thanks for all the help!

That's great! But, I guess I should have provided a better example for 
my problem. The reason being that I did not consider strings. For 
instance, in my case, I'm actually trying to add a value to a data frame 
that looks like this:

Obs     X
0     NA
1     "01 001"
2     "01 002"
3     "01 003"

And I am actually trying to get that specific "NA" value and convert it 
to "00 000" so it can look like this:

Obs     X
0     "00 000"
1     "01 001"
2     "01 002"
3     "01 003"

When I write the code you provided, I get this result:

x[1,"X"]<-"00 000"
Warning message:
In `[<-.factor`(`*tmp*`, iseq, value = c(NA, 3L, 4L, 5L, 6L, 7L,  :

invalid factor level, NAs generated

I am wondering what I am doing wrong and how to solve this problem.

Thanks for all the help!

Carlos



On 6/10/2011 8:34 PM, jholtman [via R] wrote:

you probably need to read the Introduction to R to understand indexing:

x

 Obs X Y Z
1   1 1 0 1
2   2 0 0 1
3   3 1 1 1
4   4 0 1 1
5   5 1 1 0
6   6 0 0 0

x[4, "Y"] <- 0
x

 Obs X Y Z
1   1 1 0 1
2   2 0 0 1
3   3 1 1 1
4   4 0 0 1
5   5 1 1 0
6   6 0 0 0


On Fri, Jun 10, 2011 at 5:42 PM, jour4life <[hidden email] 
</user/SendEmail.jtp?type=node&node=3589793&i=0>> wrote:

Hello all,

I am wondering if there is a way to change the value of one cell in 

R. For

instance let's say I have a hypothetical data frame that looks like 

this:

Obs X Y Z
1    1 0 1
2    0 0 1
3    1 1 1
4    0 1 1
5    1 1 0
6    0 0 0

I would like to change the value of the 4th observation in the Y 

column from

1 to 0. It should look like this:

Obs X Y Z
1    1 0 1
2    0 0 1
3    1 1 1
4    0 0 1
5    1 1 0
6    0 0 0

Is it possible to change the value in one command?

Thanks,

Carlos


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