[R] Odp: Using NULL to my data?

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 09.05.2011 16:07:27:

> Nilza BARROS <nilzabarros at gmail.com> 
> Odeslal: r-help-bounces at r-project.org
> 
> 09.05.2011 16:07
> 
> 
> Dear R users,
> 
> I am reading data from a file where there are some missing that are
> represented by -9999.00.
> I am using the command below.
> =====My original data ===========
> 
> PARM = TMPC;T12X;T12N;DWPC;PALT;SKNT;DRCT;P24M;CLCL
> 
> 
>     STN    YYMMDD/HHMM      TMPC     T12X     T12N     DWPC     PALT
> SKNT
>                             DRCT     P24M     CLCL
>  820420    110429/1200     22.50 -9999.00    22.40    22.20 -9999.00
> 0.00
>                             0.00    84.00     4.00
>  820980    110429/1200     26.90 -9999.00    23.40    24.10  1010.20
> 2.91
>                           360.00     2.00     6.00
>  821130    110429/1200     24.30 -9999.00    23.30    23.70 -9999.00
> 1.94
>                           230.00     3.00     4.00
>  821410    110429/1200     24.40 -9999.00    23.70    24.20  1011.80
> 2.91
> ===========
> 
> dados<-read.table
> ("2011042912_teste.dat",sep='',fill=TRUE,na.strings="-9999.00",skip=4)
> head(dados)
>       V1          V2   V3 V4   V5   V6     V7   V8 group
> 1 820420 110429/1200 22.5 NA 22.4 22.2     NA 0.00     1
> 2      0       84.00  4.0 NA   NA   NA     NA   NA     1
> 3 820980 110429/1200 26.9 NA 23.4 24.1 1010.2 2.91     2
> 4    360        2.00  6.0 NA   NA   NA     NA   NA     2
> 5 821130 110429/1200 24.3 NA 23.3 23.7     NA 1.94     3
> 6    230        3.00  4.0 NA   NA   NA     NA   NA     3
> =============
> After some procedures a have the data as below:
> > head(Alldados)
> 
> 
>   Station_NO       date1 T_2M TMAX_2M TMIN_2M TD_2M     PS FF_10M DD_10M
> 1     820420 110429/1200 22.5      NA    22.4  22.2     NA   0.00      0
> 2     820980 110429/1200 26.9      NA    23.4  24.1 1010.2   2.91    360
> 3     821130 110429/1200 24.3      NA    23.3  23.7     NA   1.94    230
> 4     821410 110429/1200 24.4      NA    23.7  24.2 1011.8   2.91    270
> 5     821450 110429/1200 28.2      NA    21.1  25.8 1008.8   0.00      0
> 6     821810 110429/1200 23.3      NA    22.8  22.9 1001.6   0.00      0
>   TOT_PRCP CLCL      date2
> 1    84.00   NA 2011042912
> 2     2.00   NA 2011042912
> 3     3.00   NA 2011042912
> 4    12.00   NA 2011042912
> 5     6.00   NA 2011042912
> 6    38.00   NA 2011042912
> 
> But  I need to feed my database. These missings should be represented by
> NULL.
> I mean, all "NA" should be replaced by "NULL" in my database.
> I am trying the command below to pick up the rows and columns with NA 
but I
> don't know how to fill the original data :
> 
> which(is.na(Alldados),arr.ind=TRUE)
> 
> But I don't know how to replace each NA with NULL. I tried using as.null 
but
> NA is not replace at all.

Why do you want that? NULL is reserved for objects which emerged from 
undefined function results. See its help page.

As such you can not have vector of NULLs.

> rep(NULL, 10)
NULL
> rep(NA, 10)
 [1] NA NA NA NA NA NA NA NA NA NA

Maybe you want to replace NA with zero. If yes 

Alldados[is.na(Alldados)]<-0

could be what you want.

Regards
Petr


> 
> I hope someone could help me.
> 
> Best Wishes,
> Nilza Barros
> 
>    [[alternative HTML version deleted]]
> 
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