Sorry for that offlist post, did not mean to do it intentionally. just hit the
wrong button. Unfortunately this disadvantage is not written next to $ in the
manual.
>
> On Apr 29, 2010, at 2:34 AM, Bunny, lautloscrew.com wrote:
>
>> David,
>>
>> With your help i finally got it. THX!
>> sorry for handing out some ugly names.
>> Reason being: it´s a german dataset with german variable names. With those
>> german names you are always sure you dont use a forbidden
>> name. I just did not want to hit one of those by accident when changing
>> these names for the mailing list. columna is just the latin term for column
>> :) . Anyway here´s what worked
>>
>> note: I just tried to use some more "real" names here.
>>
>> recode_items = function(dataframe,question_number,medium=3){
>>
>> #note column names of the initial data.frame are like
>> Question1,Question2 etc. Using [,1] would not be very practical since
>> # the df contains some other data too. Indexing by names seemed to most
>> comfortable way so far.
>> question<-paste("Question",question_number,sep="")
>> # needed indexing here that understands characters, that´s why
>> going with [,question_number] did not work.
>> dataframe[question][dataframe[question]==3]=0
>
> This would be more typical:
>
> dataframe[dataframe[question]==3, question] <- 0
>
>>
>>
>> return(dataframe)
>>
>> }
>>
>> recode_items(mydataframe,question_number,3)
>> # this call uses the dataframe that contains the answers of survey
>> participants. Question number is an argument that selects the question from
>> the dataframe that should be recoded. In surveys some weighting schemes only
>> respect extreme answers, which is why the medium answer is recoded to zero.
>> Since it depends on the item scale what medium actually is, I need it to be
>> an argument of my function.
>>
>>> Did you want a further logical test with that "=1" or some sort of
>>> assignment???
>>
>> So yes, it´s an assignment.
>>
>>>> Moral: Generally better to use "[" indexing.
>>
>> That´s what really made my day (and it´s only 9.30 a.m. here ) . Are there
>> exceptions to rule?
>
> Not that I know of.
>
>> I just worked a lot with the $ in the past.
>
> "$colname" is just syntactic sugar for either "["colname"]" or "[
> ,"colname"]" and it has the disadvantage that colname is not evaluated.
>
>
>>
>> thx
>>
>> matt
>>
>>
>>
>>
>> On 29.04.2010, at 00:56, David Winsemius wrote:
>>
>>>
>>> On Apr 28, 2010, at 5:45 PM, David Winsemius wrote:
>>>
>>>>
>>>> On Apr 28, 2010, at 5:31 PM, Bunny, lautloscrew.com wrote:
>>>>
>>>>> Dear all,
>>>>>
>>>>> i have a problem with processing dataframes within a function using the
>>>>> "$".
>>>>> Here´s my code:
>>>>>
>>>>>
>>>>> recode_items = function(dataframe,number,medium=2){
>>>>>
>>>>> # this works
>>>>> q<-paste("columna",number,sep="")
>>>>
>>>> Do your really want q to equal "columna2" when "number" equals 2?
>>>>
>>>>>
>>>>> # this does not work, particularly because "dataframe" is not processed
>>>>> # dataframe should be: givenframe$columnagivennumber
>>>>> a=dataframe$q[dataframe$q==medium]=1
>>>
>>> Did you want a further logical test with that "=1" or some sort of
>>> assignment???
>>>
>>>>
>>>> a) Do you want to work on the column from dataframe ( horrible name for
>>>> this purpose IMO) with the name "columna2"? If so, then start with
>>>>
>>>> dataframe[ , q ]
>>>>
>>>> .... the "q" will be evaluated in this form whereas it would not when used
>>>> with "$".
>>>>
>>>> b) (A guess in absence of explanation of a goal.) Now do you want all of
>>>> the rows where that vector equals "medium"? If so ,then try this:
>>>>
>>>> dataframe[ dataframe[ , q ]==2 , ] # untested in the absence of data
>>>
>>> Ooops. should have been:
>>>
>>> dataframe[ dataframe[ , q ]==medium , ] #since both q and medium will be
>>> evaluated.
>>>
>>>
>>>>
>>>> Moral: Generally better to use "[" indexing.
>>>>
>>>> --
>>>> David.
>>>>
>>>>
>>>>>
>>>>>
>>>>> return(a)
>>>>>
>>>>> }
>>>>>
>>>>>
>>>>> If I call this function, i´d like it to return my dataframe. The
>>>>> problem appears to be somewhere around the $. I´m sure this not too hard,
>>>>> but somehow i am stuck. I´ll keep searchin the manuals.
>>>>> Thx for any help in advance.
>>>>>
>>>>> best
>>>>>
>>>>> matt
>>>>> [[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.
>>>>
>>>> ______________________________________________
>>>> 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.
>>>
>>
>
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