[R] Populating then sorting a matrix and/or data.frame

[Noah Silverman]

Still doesn't work.

When using rbind to build the data.frame, it get a structure mostly full 
of NA.
The data is correct, so something about pushing into the data.frame is 
breaking.

Example code:
results <- data.frame()

for(i in 1:n){
     #do all the work
     #a is a test label. b,c,d are numeric.
     results <- rbind(results, c(a,b,c,d))
}



On 11/11/10 2:00 AM, Michael Bedward wrote:
> You can use rbind as in your original post, but if you've got a mix of
> character and numeric data start with a data.frame rather than a
> matrix.
>
> Michael
>
> On 11 November 2010 20:30, Noah Silverman<noah at smartmediacorp.com>  wrote:
>> That makes perfect sense.
>>
>> Since I need to build up the results table sequentially as I iterate through
>> the data, how would you recommend it??
>>
>> Thanks,
>>
>> -N
>>
>> On 11/11/10 12:03 AM, Michael Bedward wrote:
>>> All values in a matrix are the same type, so if you've set up a matrix
>>> with a character column then your numeric values will also be stored
>>> as character. That would explain why they are being converted to
>>> factors.  It would also explain why your query isn't working.
>>>
>>> Michael
>>>
>>>
>>> On 11 November 2010 18:40, Noah Silverman<noah at smartmediacorp.com>    wrote:
>>>> That was a typo.
>>>>
>>>> It should have read:
>>>> results[results$one<    100,]
>>>>
>>>> It does still fail.
>>>>
>>>> There is ONE column that is text.  So my guess is that R is seeing that
>>>> and
>>>> assuming that the entire data.frame should be factors.
>>>>
>>>> -N
>>>>
>>>> On 11/10/10 11:16 PM, Michael Bedward wrote:
>>>>> Hello Noah,
>>>>>
>>>>> If you set these names...
>>>>>> names(results)<- c("one", "two", "three")
>>>>> this won't work...
>>>>>> results[results$c<      100,]
>>>>> because you don't have a column called "c" (unless that's just a typo
>>>>> in your post).
>>>>>
>>>>>> I tried making it a data.frame with
>>>>>> foo<- data.frame(results)
>>>>>>
>>>>>> But that converted all the numeric values to factors!!!
>>>>> Not sure what's going on there. If 'results' is a numeric matrix you
>>>>> should get a data.frame with numeric cols since under the hood this is
>>>>> just calling the as.data.frame function.
>>>>>
>>>>> Michael
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 11 November 2010 16:02, Noah Silverman<noah at smartmediacorp.com>
>>>>>   wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I have a process in R that produces a lot of output.  My plan was to
>>>>>> build
>>>>>> up a matrix or data.frame "row by row", so that I'll have a nice object
>>>>>> with
>>>>>> all the resulting data.
>>>>>>
>>>>>> I started with:
>>>>>> results<- matrix(ncol=3)
>>>>>> names(results)<- c("one", "two", "three")
>>>>>>
>>>>>> Then, when looping through the data:
>>>>>> results<- rbind(results, c(a,b,c))
>>>>>>
>>>>>> This seems to work fine. BUT, my problem arises when I want to filter,
>>>>>> sort,
>>>>>> etc.
>>>>>>
>>>>>> I tried (thinking like a data.frame):
>>>>>> results[results$c<      100,]
>>>>>>
>>>>>> But that fails.
>>>>>>
>>>>>> I tried making it a data.frame with
>>>>>> foo<- data.frame(results)
>>>>>>
>>>>>> But that converted all the numeric values to factors!!!  Which causes a
>>>>>> whole mess of problems.
>>>>>>
>>>>>> Any ideas??
>>>>>>
>>>>>> -N
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help at 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.
>>>>>>
>>