[R] data.frame with NA

Pietro freerisk3 at gmail.com
Tue Mar 19 12:10:00 CET 2013 

Yes, colClasses is the solution. Thank you very much.
However i found a very strange thing.

If i use:
Foglio1 <- read.xlsx2("mydb.xlsx", 1, colClasses=c("Date", rep("numeric",14)))

i get numeric dataframe, as you said.

I also get NaN (and not NA).

At this point i use the function:
Foglio1 = na.locf(Foglio1,fromLast=T) and it works perfectly. All NaN 
's were replaced with the first numeric value, as expected.

And now the enigma.

After na.locf function, Foglio1 become all CHR again! It seems that 
na.locf  convert from num to chr. Even Date is converted in chr.
I'm reading the help of this function but i can't find trace about 
the possibility of this conversion.

It seems that i can't get in anyway a numeric dataframe without NA o NaN!
Ok, i admit that i'm a newbie, but i'm trying every day to gain 
confidence with R

Can i ask you the courtesy to use na.locf function to see if also on 
your computer this function convert all to CHR?

Thank you



At 21.37 18/03/2013, David L Carlson wrote:
>It appears that you MUST use the colClasses= argument with read.xlsx2:
>
>Foglio1 <- read.xlsx2("mydb.xlsx", 1, colClasses=c("Date", rep("numeric",
>14)))
>
>However, e and n are converted to NaN not NA so you would need to convert
>those columns (at least, I didn't check for missing values in the other
>columns):
>
> > Foglio1$e <- ifelse(is.nan(Foglio1$e), NA, Foglio1$e)
> > Foglio1$n <- ifelse(is.nan(Foglio1$n), NA, Foglio1$n)
> > str(Foglio1)
>'data.frame':   1489 obs. of  15 variables:
>  $ Date: Date, format: "2001-08-17" "2001-08-20" ...
>  $ a   : num  202 201 202 201 202 ...
>  $ b   : num  231 230 230 230 232 ...
>  $ c   : num  177 179 181 180 182 ...
>  $ d   : num  277 277 276 276 275 ...
>  $ e   : num  NA NA NA NA NA NA NA NA NA NA ...
>  $ f   : num  275 277 279 279 279 ...
>  $ g   : num  91.7 90.7 90.8 91.1 91 ...
>  $ h   : num  11446 11258 11280 11396 11127 ...
>  $ i   : num  388 389 393 392 393 ...
>  $ l   : num  93.2 94 92.4 93.4 93.1 ...
>  $ m   : num  128 127 126 129 130 ...
>  $ n   : num  NA NA NA NA NA NA NA NA NA NA ...
>  $ o   : num  133 133 133 133 133 ...
>  $ p   : num  107 107 107 107 107 ...
>
>-------
>David
>
>
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > project.org] On Behalf Of David L Carlson
> > Sent: Monday, March 18, 2013 3:22 PM
> > To: 'Pietro'; 'Berend Hasselman'
> > Cc: r-help at stat.math.ethz.ch
> > Subject: Re: [R] data.frame with NA
> >
> > Try this
> >
> > Open the spreadsheet in Excel. Select all of the data click Copy. Don't
> > close Excel.
> >
> > Open R and type the following command:
> >
> > > Foglio1 <- read.table("clipboard-128", header=TRUE, sep="\t")
> >
> > Now take a look at the structure of the data.frame
> >
> > > str(Foglio1)
> > 'data.frame':   1489 obs. of  15 variables:
> >  $ Date: Factor w/ 1489 levels "1/10/2002","1/10/2003",..: 1275 1291
> > 1295
> > 1299 1304 1309 1321 1325 1329 1337 ...
> >  $ a   : num  202 201 202 201 202 ...
> >  $ b   : num  231 230 230 230 232 ...
> >  $ c   : num  177 179 181 180 182 ...
> >  $ d   : num  277 277 276 276 275 ...
> >  $ e   : num  NA NA NA NA NA NA NA NA NA NA ...
> >  $ f   : num  275 277 279 279 279 ...
> >  $ g   : num  91.7 90.7 90.8 91.1 91 ...
> >  $ h   : num  11446 11258 11280 11396 11127 ...
> >  $ i   : num  388 389 393 392 393 ...
> >  $ l   : num  93.2 94 92.4 93.4 93.1 ...
> >  $ m   : num  128 127 126 129 130 ...
> >  $ n   : num  NA NA NA NA NA NA NA NA NA NA ...
> >  $ o   : num  133 133 133 133 133 ...
> >  $ p   : num  107 107 107 107 107 ...
> >
> > ----------------------------------------------
> > David L Carlson
> > Associate Professor of Anthropology
> > Texas A&M University
> > College Station, TX 77843-4352
> >
> > > -----Original Message-----
> > > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > > project.org] On Behalf Of Pietro
> > > Sent: Monday, March 18, 2013 1:57 PM
> > > To: Berend Hasselman
> > > Cc: r-help at stat.math.ethz.ch
> > > Subject: Re: [R] data.frame with NA
> > >
> > > Yes, it's true Berend!
> > >
> > > What i do is simply use read.xlsx  function
> > >
> > > db <- read.xlsx2("c:/mydb.xlsx",1,as.data.frame=T)
> > >
> > > This is excel file i use:
> > > http://dl.dropbox.com/u/102669/mydb.xlsx
> > >
> > > I can't find  a way to import as numeric.
> > > My objective is to be able to work (in R) with my NA's
> > >
> > >
> > > At 18.46 18/03/2013, Berend Hasselman wrote:
> > >
> > > >On 18-03-2013, at 16:49, Pete <freerisk3 at gmail.com> wrote:
> > > >
> > > > >
> > > > > I have this little data.frame
> > > > >
> > > > > http://dl.dropbox.com/u/102669/nanotna.rdata
> > > > >
> > > > > Two column contains NA, so the best thing to do is use na.locf
> > > > function (with
> > > > > fromLast = T)
> > > > >
> > > > > But locf function doesn't work because NA in my data.frame are
> > > > not recognized as
> > > > > real NA.
> > > > >
> > > > > Is there a way to substitute fake NA with real NA? In this case
> > > > na.locf function
> > > > > should work
> > > > >
> > > >
> > > >Your data are all characters. Do
> > > >
> > > >str(db)
> > > >
> > > >to see that. What is probably supposed to be numeric is also
> > > character,
> > > >Somehow you have managed to read in data that R thinks is all chr.
> > > >Your NA are "NA" in reality: a character string "NA".
> > > >
> > > >You will have to review the method you used to get the data into R.
> > > >And make sure that what you want to be numeric is indeed numeric.
> > > >Then you can start to think about doing something about the NA's.
> > > >
> > > >Berend
> > >
> > > ______________________________________________
> > > 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.
> >
> > ______________________________________________
> > 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.

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