[R] how to get a value from a list (using paste function)?

[jim holtman]

it is also a fortune.

> fortune('parse')

If the answer is parse() you should usually rethink the question.
   -- Thomas Lumley
      R-help (February 2005)



On Thu, Dec 27, 2012 at 5:44 AM, Heramb Gadgil <heramb.gadgil at gmail.com> wrote:
> I am not sure why "Never ever!"
>
> Can you please elaborate. What are the negatives about the method
>
> Warm Regards,
> Heramb M. Gadgil
>
>
> On Thu, Dec 27, 2012 at 3:50 PM, Uwe Ligges <ligges at statistik.tu-dortmund.de
>> wrote:
>
>>
>>
>> On 27.12.2012 08:09, Heramb Gadgil wrote:
>>
>>> eval(parse(text=paste0("**cvtest$",lambda.rule)))
>>>
>>
>> No, never ever!
>>
>> There is an R idiom made for it:
>>
>> cvtest[[lambda.rule]]
>>
>> Uwe Ligges
>>
>>
>>
>>
>>
>>
>>
>>  I hope this works.
>>>
>>> On Wed, Dec 19, 2012 at 12:57 AM, Thomas Stewart
>>> <tgs.public.mail at gmail.com>**wrote:
>>>
>>>  Soyeon-
>>>>
>>>> A possible solution:
>>>>
>>>> get(lambda.rule,envir=**list2env(cvtest))
>>>>
>>>>
>>>> On Tue, Dec 18, 2012 at 12:34 PM, Soyeon Kim <yunni0731 at gmail.com>
>>>> wrote:
>>>>
>>>>  Dear my R friends,
>>>>>
>>>>> I want to get a number from a list using paste function.
>>>>> In my example,
>>>>> lambda.rule <- "lambda.1se"
>>>>> cvtest is a list (result from cv.glmnet)
>>>>> and
>>>>> cvtest$lambda.1se
>>>>> [1] 1.308973
>>>>>
>>>>> I want to call the value using paste function.
>>>>> I used get function but there was an error.
>>>>> test <-  get(paste("cvtest$",lambda.**rule, sep=""))
>>>>> Error in get(paste("cvtest$", lambda.rule, sep = "")) :
>>>>>    object 'cvtest$lambda.1se' not found
>>>>>
>>>>> Do you guys know how to solve this issue?
>>>>>
>>>>> Thank you so much in advance and merry Christmas!
>>>>>
>>>>> Soyeon
>>>>>
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>>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>>
>>>>>
>>>>>
>>>>>
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>>>>
>>>>
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>
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-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.