dataset[ nrow(dataset), ] <- c ("Male", 5, "bad")

The above seems to have worked to append a row in place of a rbind(). This
method does not drop the custom attributes from the column. Do yo see any
issue with this method.

Thanks,
Sammy

On Sat, Nov 12, 2011 at 10:16 PM, David Winsemius <dwinsemius@comcast.net>wrote:

>
> On Nov 12, 2011, at 6:40 PM, Sammy Zee wrote:
>
>  Thanks David. Besides rbind(), is there any other way to add a row to a
>> data frame so that I do not lose the custom attributes.
>>
>
> I have already told you the method that I know of. You don't seem to have
> taken my poin that it is not a data.frame specific problem but rahter a
> facor problem. You are welcome to redefine `rbind.data.frame`. The R
> language is rather flexible in that manner.
>
> --
> David.
>
>
>> Thanks,
>> Sammy
>>
>> On Sat, Nov 12, 2011 at 5:17 PM, David Winsemius <dwinsemius@comcast.net>
>> wrote:
>>
>> On Nov 12, 2011, at 2:47 PM, Sammy Zee wrote:
>>
>> When I use rbind() or rbind.data.frame() to add a row to an existing
>> dataframe, it appears that attributes for the column of type "factor" are
>> dropped. See the sample example below to reproduce the problem. Please
>> suggest How I can fix this.
>>
>>
>> Thanks,
>> Sammy
>>
>> a=c("Male", "Male", "Female", "Male")
>> b=c(1,2,3,4)
>> c=c("great", "bad", "good", "bad")
>> dataset<- data.frame (gender = a, count = b, answer = c)
>>
>> dataset
>>
>> gender count answer
>> 1   Male     1  great
>> 2   Male     2    bad
>> 3 Female     3   good
>> 4   Male     4    bad
>>
>>
>> attributes(dataset$answer)
>> $levels
>> [1] "bad"   "good"  "great"
>>
>> $class
>> [1] "factor"
>>
>> Now adding some custom attributes to column dataset$answer
>>
>> attributes(dataset$answer)<-c(**attributes(dataset$answer),**
>> list(newattr1="custom-attr1"))
>> attributes(dataset$answer)<-c(**attributes(dataset$answer),**
>> list(newattr2="custom-attr2"))
>>
>> If you look through the code of rbind.data.frame you see that column
>> values are processed with the 'factor' function.
>>
>>
>> > attributes(dataset$answer)
>> $levels
>> [1] "bad"   "good"  "great"
>>
>> $class
>> [1] "factor"
>>
>> $newattr1
>> [1] "custom-attr1"
>>
>> $newattr2
>> [1] "custom-attr2"
>>
>> > attributes(factor(dataset$**answer))
>>
>> $levels
>> [1] "bad"   "good"  "great"
>>
>> $class
>> [1] "factor"
>>
>>
>> So I think you are out of luck. You will need to restore the "special
>> attributes" yourself.
>>
>> --
>> David.
>>
>>
>> attributes(dataset$answer)
>> $levels
>> [1] "bad"   "good"  "great"
>>
>> $class
>> [1] "factor"
>>
>> $newattr1
>> [1] "custom-attr1"
>>
>> $newattr2
>> [1] "custom-attr2"
>>
>> However as soon as I add a row to this data frame ("dataset") by rbind(),
>> it loses the custom
>> attributes ("newattr1" and "newattr2") I have just added
>>
>> newrow = c(gender="Female", count = 5, answer = "great")
>>
>> dataset <- rbind(dataset, newrow)
>>
>> attributes(dataset$answer)
>> $levels
>> [1] "bad"   "good"  "great"
>>
>> $class
>> [1] "factor"
>>
>> the two custom attributes are dropped!! Any suggestion why this is
>> happening.
>>
>> On Fri, Nov 11, 2011 at 11:44 AM, Jeff Newmiller
>> <jdnewmil@dcn.davis.ca.us>**wrote:
>>
>> As the doctor says, if it hurts "don't do that".
>>
>> A factor is a sequence of integers with a corresponding list of character
>> strings. Factors in two separate vectors can and usually do map the same
>> integer to different strings, and R cannot tell how you want that
>> resolved.
>>
>> Convert these columns to character before combining them, and only convert
>> to factor when you have all of your possibilities present (or you specify
>> them in the creation of the factor vector).
>> ------------------------------**------------------------------**
>> ---------------
>> Jeff Newmiller                        The     .....       .....  Go
>> Live...
>>
>> Sammy Zee <szee2007@gmail.com> wrote:
>>
>> Hi all,
>>
>> When I use rbind() or rbind.data.frame() to add a row to an existing
>> dataframe, it appears that attributes for the column of type "factor"
>> are
>> dropped. I see the following post with same problem. However i did not
>> see
>> any reply to the following posting offering a solution. Could someone
>> please help.
>>
>>
>> http://r.789695.n4.nabble.com/**rbind-data-frame-drops-**
>> attributes-for-factor-**variables-td919575.html<http://r.789695.n4.nabble.com/rbind-data-frame-drops-attributes-for-factor-variables-td919575.html>
>>
>> Thanks,
>> Sammy
>>
>>    [[alternative HTML version deleted]]
>>
>> ___
>>
>>
> David Winsemius, MD
> West Hartford, CT
>
>

	[[alternative HTML version deleted]]

