[R] Taking the sum of only some columns of a data frame

[Jeff Newmiller]

You can also look at the knitr-RMarkdown work flow, or the knitr-latex work flow. In both of these it is reasonable to convert your data frame to a temporary character-only form purely for output purposes. However, one can usually use an existing function to push your results out without damaging your working data. 

It is important to separate your data from your output because mixing results (totals) with data makes using the data further extremely difficult. Mixing them is one of the major flaws of the spreadsheet model of computation, and it causes problems there as well as in R.
-- 
Sent from my phone. Please excuse my brevity.

On March 31, 2017 1:05:09 PM PDT, William Michels via R-help <r-help at r-project.org> wrote:
>Again, you should always copy the R-help list on replies to your OP.
>
>The short answer is you **shouldn't** replace NAs with blanks in your
>matrix or dataframe.  NA is the proper designation for those cell
>positions. Replacing NA with a "blank" in a dataframe will convert
>that column to a "character" mode, precluding further numeric
>manipulation of those columns.
>
>Consider your workflow:  are you tying to export a table? If so, take
>a look at installing pander (see 'missing' argument on webpage below):
>
>https://cran.r-project.org/web/packages/pander/README.html
>
>Finally, please review the Introductory PDF, available here:
>
>https://cran.r-project.org/doc/manuals/R-intro.pdf
>
>HTH, Bill.
>
>William Michels, Ph.D.
>
>
>
>On Fri, Mar 31, 2017 at 11:21 AM, BR_email <br at dmstat1.com> wrote:
>> William:
>> How can I replace the "NAs" with blanks?
>> Bruce
>>
>> Bruce Ratner, Ph.D.
>> The Significant Statistician™
>>
>>
>> William Michels wrote:
>>>
>>> I'm sure there are more efficient ways, but this works:
>>>
>>>> test1 <- matrix(runif(50), nrow=10, ncol=5)
>>>> ## test1 <- as.data.frame(test1)
>>>> test1 <- rbind(test1, NA)
>>>> test1[11, c(1,3)] <- colSums(test1[1:10,c(1,3)])
>>>> test1
>>>
>>>
>>> HTH,
>>>
>>> Bill.
>>>
>>> William Michels, Ph.D.
>>>
>>>
>>>
>>> On Fri, Mar 31, 2017 at 9:20 AM, Bruce Ratner PhD <br at dmstat1.com>
>wrote:
>>>>
>>>> Hi R'ers:
>>>> Given a data.frame of five columns and ten rows.
>>>> I would like to take the sum of, say, the first and third columns
>only.
>>>> For the remaining columns, I do not want any calculations, thus
>rending
>>>> their "values" on the "total" row blank. The sum/total row is to be
>combined
>>>> to the original data.frame, yielding a data.frame with five columns
>and
>>>> eleven rows.
>>>>
>>>> Thanks, in advance.
>>>> Bruce
>>>>
>>>>
>>>> ______________
>>>> Bruce Ratner PhD
>>>> The Significant Statistician™
>>>>
>>>>
>>>>
>>>>
>>>>          [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>>
>>
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>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.