[R] Converting a string to variable names

[Jim Lemon]

Hi Ruiyang,
In this case you don't want the "get", just the strings produced by "paste":

mydf<-data.frame(col1=LETTERS[1:10],col2=1:10)
rownames(mydf)<-paste("P",mydf$col1,sep="")

Jim

On Thu, Nov 16, 2017 at 9:22 AM, 刘瑞阳 <ruiyangliu94 at gmail.com> wrote:
> Hi,
>
> Thanks for your reply.
>
> I just came up with another question about a similar but different thing:
>
> Say I have a bunch of data.frame variables named P1,P2,P3… I want to assign them row names according to symbols in the first column, and I want to do this using a for loop. How could I accomplish this?
>
>
> for (test_sample in c(1:10)){
> + x<-as.name(paste(“P",as.character(test_sampel),sep=""))
> + rownames(x)<-get((paste(“P”,as.character(test_sample),sep="")))[,1]
> + }
>
> This would not work probably because x is simply a name instead of a data.frame variable(Error: "attempt to set 'rownames' on an object with no dimensions"). But I could not find the right way out… How should I solve it?
>
> Thanks!
>
> Ruiyang
>
>
>> On Nov 14, 2017, at 4:39 PM, Jim Lemon <drjimlemon at gmail.com> wrote:
>>
>> Hi Ruiyang,
>> I think you want "get":
>>
>> For (index in seq(1,16)){
>> plot(x=(a given set of value),y=get(paste(“PC”,as.character(index),sep=“”)))
>> }
>>
>> On Wed, Nov 15, 2017 at 7:43 AM, 刘瑞阳 <ruiyangliu94 at gmail.com> wrote:
>>> Hi,
>>> Suppose that I want to do a series of plots with the y value for each plot as PC1, PC2, PC3… How could I accomplish this using a for loop?
>>> Suppose the code like this:
>>>
>>> For (index in seq(1,16)){
>>> plot(x=(a given set of value),y=paste(“PC”,as.character(index),sep=“”)
>>> }
>>>
>>> But this would not work because y is assigned a string instead of the variable names. So how could I assign y with a variable name instead of a string? Your reply would be appreciated!
>>> Ruiyang Liu
>>> ______________________________________________
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>
> ______________________________________________
> 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.