R help - Nov 2011 - Is there way to add a new row to a data frame in a specific location

Is there easy way (without copying the existing rows to a temporary
location and copying back) to add a new row to a specific index location in
an existing data frame?

Example

df = data.frame( A= c('a','b','c'), B=c(1,2,3),
C=(10,20,30))

newrow = c('X', 100, 200)

I want to add the newrow as the second row to the data frame df

Please suggest a solution that is efficient for a data frame that can have
millions of rows, and I want to add a new row in any given index location
of the data frame.

Thanks,
Sammy

	[[alternative HTML version deleted]]

Hi.
May be this:

df = data.frame( A=c('a','b','c'), B=c(1,2,3),
C=c(10,20,30),
stringsAsFactors=FALSE)

newrow = c('X', 100, 200)

rbind(df,newrow)[c(1,4,2,3),]

Andrija


On Thu, Nov 24, 2011 at. 6:05 PM, Sammy Zee <szee2007@gmail.com> wrote:
> Is there easy way (without copying the existing rows to a temporary
> location and copying back) to add a new row to a specific index location in
> an existing data frame?
>
> Example
>
> df = data.frame( A= c('a','b','c'), B=c(1,2,3),
C=(10,20,30))
>
> newrow = c('X', 100, 200)
>
> I want to add the newrow as the second row to the data frame df
>
> Please suggest a solution that is efficient for a data frame that can have
> millions of rows, and I want to add a new row in any given index location
> of the data frame.
>
> Thanks,
> Sammy
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
	[[alternative HTML version deleted]]

AFAIK all solutions to the "grow object size" problem in R involve
creation of a new object to "change" an old one.  There is
considerable sophistication under the hood that allows a minimum of intermediate
objects to be created if you are careful, but actually changing the size of an
object in place is not supported.

That doesn't mean that you have to "copy... to a temporary and then
copy back", since you can reference chunks of an existing object without
actually moving them in memory by using indexing. But (AFAIK) you cannot escape
creating at least one new copy of the data that "becomes" the object
if you use rbind to grow your object.
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Sammy Zee <szee2007 at gmail.com> wrote:
>Is there easy way (without copying the existing rows to a temporary
>location and copying back) to add a new row to a specific index
>location in
>an existing data frame?
>
>Example
>
>df = data.frame( A= c('a','b','c'), B=c(1,2,3),
C=(10,20,30))
>
>newrow = c('X', 100, 200)
>
>I want to add the newrow as the second row to the data frame df
>
>Please suggest a solution that is efficient for a data frame that can
>have
>millions of rows, and I want to add a new row in any given index
>location
>of the data frame.
>
>Thanks,
>Sammy
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

This look really interesting but I don't understand what is happening.
Please can someone explain the last line and what the bit in [] is doing.
Ian

df = data.frame( A=c('a','b','c'), B=c(1,2,3),
C=c(10,20,30),
stringsAsFactors=FALSE)

newrow = c('X', 100, 200)

rbind(df,newrow)[c(1,4,2,3),]