[R-sig-Epi] converting string to a object name of a dataset

[Madan Gopal Kundu]

Thanks a lot for your help. Yeah it was a mistake from my end only.

Regards
Madan Gopal Kundu
On Fri, Mar 18, 2011 at 1:19 PM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Mar 18, 2011, at 11:18 AM, Madan Gopal Kundu wrote:
>
>> Hi,
>>
>> Thanks to David and Bendix for giving me the solution. I would like to
>> extend my question little bit further. I am trying to execute
>> following code:
>>
>> data1<- data.frame(x=c(1:4), y=rep(1:4))
>
> Did you mean to type:
>
>  data1<- data.frame(x=c(1:4), y=rep(1, 4))  # ?
>
>> data1
>  x y
> 1 1 1
> 2 2 1
> 3 3 1
> 4 4 1
>
>> gvars<- c("x", "y")
>> for (i in 1:2)
>> {
>> print(data1[[gvars[i]]])
>> }
>>
>> and it returns the following output:
>> [1] 1 2 3 4
>> [1] 1 2 3 4
>>
>> However, my desired output is
>> [1] 1 2 3 4
>> [1] 1 1 1 1
>>
>> I tried the following code as well, but the problem remains same:
>> attach(data1)
>> for (i in 1:2)
>> {
>> print(get(gvars[i]))
>> }
>>
>> Thanks in advance!!
>>
>> Regards
>> Madan
>>
>> On Fri, Mar 18, 2011 at 3:19 AM, BXC (Bendix Carstensen) <bxc at steno.dk>
>> wrote:
>>>
>>> get() looks in the search path, so you can put data 1 there using
>>> attach():
>>>
>>>> data1<- data.frame(x=c(1:4), y=rep(1,4))
>>>> attach(data1)
>>>> gvars<- c("x", "y")
>>>> get( gvars[1] )
>>>
>>> [1] 1 2 3 4
>>>>
>>>> get( gvars[2] )
>>>
>>> [1] 1 1 1 1
>>>
>>> Best regards,
>>> Bendix Carstensen
>>> _________________________________________
>>>
>>> Bendix Carstensen
>>> Senior Statistician
>>> Steno Diabetes Center A/S
>>> Niels Steensens Vej 2-4
>>> DK-2820 Gentofte
>>> Denmark
>>> +45 44 43 87 38 (direct)
>>> +45 30 75 87 38 (mobile)
>>> bxc at steno.dk    www.biostat.ku.dk/~bxc
>>> www.steno.dk
>>>
>>>> -----Original Message-----
>>>> From: r-sig-epi-bounces at r-project.org
>>>> [mailto:r-sig-epi-bounces at r-project.org] On Behalf Of Madan
>>>> Gopal Kundu
>>>> Sent: 18. marts 2011 06:19
>>>> To: r-sig-epi at r-project.org
>>>> Subject: [R-sig-Epi] converting string to a object name of a dataset
>>>>
>>>> Hi,
>>>>
>>>> I am trying to access object which is variable of a dataset
>>>> using string.  For that I am trying to convert a string to
>>>> the object name in the following code. But unfortunately it
>>>> looks something is going wrong in the following code.
>>>>
>>>> data1<- data.frame(x=c(1:4), y=rep(1:4))
>>>> gvars<- c("x", "y")
>>>> z<- paste("data1", gvars[1], sep="$")
>>>> get(z)
>>>>
>>>> The above code should return following output:
>>>> [1] 1 2 3 4
>>>>
>>>> but instead it is printing following error "Error in get(z) :
>>>> object 'data1$x' not found"
>>>>
>>>> Please help me to fix the problem.
>>>>
>>>> Regards
>>>> Madan
>>>>
>>>> _______________________________________________
>>>> R-sig-Epi at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-epi
>>>>
>
> David Winsemius, MD
> West Hartford, CT
>
>