[R] Adding a column into the file

[David Winsemius]

On Jun 1, 2012, at 12:27 PM, pigpigmeow wrote:

> Dear all,
> I have a lot of problems on R-programming.
> for example
> my csv. file is ..

That certainly does not look like any csv file I have ever seen.

> Date                  wrfRH wrfsolar wrfwindspeed wrfrain wrftd wrfta
> 21/10/2010 92.97 22.11 53.27 0 1546.337861 61.00852664
> 22/10/2010 87.35 21.99 40.89 0 1300.408288 62.85352227
> 23/10/2010 88.38 21.71 28.04 0.01 1381.768284 54.80594493
> 24/10/2010 92.32 15.45 22.38 0.51 1113.90981 39.46573663
> 25/10/2010 93.42 21.59 35.5 0.52 868.4895334 28.42952321
> 26/10/2010 93.38 20.15 42.58 0.07 1404.722837 40.29300856
> i calculate the ratio of wrfRH/wrfsolar for each day.
>

If you are confused in your terminology, and you really have a  
data.frame created by read.table, then adding a column to an existing  
data.frame , say the ratio of wrftd divided by wrfta,  is really simple:

dfrm$ratio <- with dfrm, wrftd/wrfta)


> that is
> Date                  wrfRH wrfsolar wrfwindspeed wrfrain wrftd  
> wrfta ratio
> 21/10/2010 92.97 22.11 53.27 0 1546.337861 61.00852664  XXXX
> 22/10/2010 87.35 21.99 40.89 0 1300.408288 62.85352227  YYYY
> 23/10/2010 88.38 21.71 28.04 0.01 1381.768284 54.80594493 ZZZZ
> 24/10/2010 92.32 15.45 22.38 0.51 1113.90981 39.46573663 AAAA
> 25/10/2010 93.42 21.59 35.5 0.52 868.4895334 28.42952321 BBBB
> 26/10/2010 93.38 20.15 42.58 0.07 1404.722837 40.29300856  CCCC
>
> how to add new column in the original file ? Anyone can help me?!
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Adding-a-column-into-the-file-tp4632093.html
> Sent from the R help mailing list archive at Nabble.com.
>

David Winsemius, MD
West Hartford, CT