R help - Apr 2018 - How to dynamically add variables to a dataframe

Hi,

I am a bit rusty with R programming and do not seem to find a solution to
add a number of variables to my existing dataframe. Basically I need to add
n=dim(d1)[1] variables to my d0 dataframe and I would like them to be named
V1, V2, V3, ... , V[dim(d1)[1])

When running the following code:

for (t in 1:dim(d1)[1]){
  d0$V[t] <- 0
}

all I get is a V variable populated with zeros...

I am sure there is a fairly straightforward code to accomplish what I need,
any suggestion?

Thank you,

Luca

	[[alternative HTML version deleted]]

Hi Luca,
How about this?

# create some dummy data since I don't have your d0 or
d1
> n  <- 3
> d0 <- data.frame(a=runif(5),b=runif(5))
# here's the suggested code
> d1 <- cbind(d0, matrix(0,nrow(d0),n))
> colnames(d1)[1:n + ncol(d0)] <-
paste("V",1:n,sep="")
HTH,
Eric


On Sun, Apr 22, 2018 at 11:13 AM, Luca Meyer <lucam1968 at gmail.com>
wrote:
> Hi,
>
> I am a bit rusty with R programming and do not seem to find a solution to
> add a number of variables to my existing dataframe. Basically I need to add
> n=dim(d1)[1] variables to my d0 dataframe and I would like them to be named
> V1, V2, V3, ... , V[dim(d1)[1])
>
> When running the following code:
>
> for (t in 1:dim(d1)[1]){
>   d0$V[t] <- 0
> }
>
> all I get is a V variable populated with zeros...
>
> I am sure there is a fairly straightforward code to accomplish what I need,
> any suggestion?
>
> Thank you,
>
> Luca
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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]]

Another option is

d0[paste0("V", 1:nrow(d1))] <- 0

--Ista

On Sun, Apr 22, 2018 at 4:23 AM, Eric Berger <ericjberger at gmail.com>
wrote:
> Hi Luca,
> How about this?
>
> # create some dummy data since I don't have your d0 or d1
>> n  <- 3
>> d0 <- data.frame(a=runif(5),b=runif(5))
>
> # here's the suggested code
>> d1 <- cbind(d0, matrix(0,nrow(d0),n))
>> colnames(d1)[1:n + ncol(d0)] <-
paste("V",1:n,sep="")
>
> HTH,
> Eric
>
>
> On Sun, Apr 22, 2018 at 11:13 AM, Luca Meyer <lucam1968 at gmail.com>
wrote:
>
>> Hi,
>>
>> I am a bit rusty with R programming and do not seem to find a solution
to
>> add a number of variables to my existing dataframe. Basically I need to
add
>> n=dim(d1)[1] variables to my d0 dataframe and I would like them to be
named
>> V1, V2, V3, ... , V[dim(d1)[1])
>>
>> When running the following code:
>>
>> for (t in 1:dim(d1)[1]){
>>   d0$V[t] <- 0
>> }
>>
>> all I get is a V variable populated with zeros...
>>
>> I am sure there is a fairly straightforward code to accomplish what I
need,
>> any suggestion?
>>
>> Thank you,
>>
>> Luca
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

Like this?
> V <- c("fee","fie","foe")
> aq <- head(airquality) # Just to get a shorter example
> aq[V] <- 0
> aq
  Ozone Solar.R Wind Temp Month Day fee fie foe
1    41     190  7.4   67     5   1   0   0   0
2    36     118  8.0   72     5   2   0   0   0
3    12     149 12.6   74     5   3   0   0   0
4    18     313 11.5   62     5   4   0   0   0
5    NA      NA 14.3   56     5   5   0   0   0
6    28      NA 14.9   66     5   6   0   0   0

> On 22 Apr 2018, at 10:13 , Luca Meyer <lucam1968 at gmail.com> wrote:
> 
> Hi,
> 
> I am a bit rusty with R programming and do not seem to find a solution to
> add a number of variables to my existing dataframe. Basically I need to add
> n=dim(d1)[1] variables to my d0 dataframe and I would like them to be named
> V1, V2, V3, ... , V[dim(d1)[1])
> 
> When running the following code:
> 
> for (t in 1:dim(d1)[1]){
>  d0$V[t] <- 0
> }
> 
> all I get is a V variable populated with zeros...
> 
> I am sure there is a fairly straightforward code to accomplish what I need,
> any suggestion?
> 
> Thank you,
> 
> Luca
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com