[R] Replace NAs in split lists

[PIKAL Petr]

Hi

library(zoo)

has function na.locf, which probably can do what you want.

so something like (untested)

sdf1.fill<-lapply(sdf1, na.locf)
do.call(rbind, sdf1.fill)

Cheers.
Petr

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ek Esawi
> Sent: Monday, January 8, 2018 4:36 AM
> To: r-help at r-project.org
> Subject: Re: [R] Replace NAs in split lists
>
> I just came up with a solution right after i posted the question, but i figured
> there must be a better and shorter one.than my solution sdf1[[1]][1,4]<-
> lapplyresults[[1]]
> sdf1[[2]][1,4]<-lapplyresults[[2]]
>
> EK
>
> On Sun, Jan 7, 2018 at 10:13 PM, Ek Esawi <esawiek at gmail.com> wrote:
> > Hi all--
> >
> > I stumbled on this problem online. I did not like the solution given
> > there which was a long UDF. I thought why cannot split and l/s apply
> > work here. My aim is to split the data frame, use l/sapply, make
> > changes on the split lists and combine the split lists to new data
> > frame with the desired changes/output.
> >
> > The data frame shown below has a column named ID which has 2 variables
> > a and b; i want to replace the NAs on the Value column by 2, which is
> > the only numeric entry, for ID=a and by 5 for ID=b.
> >
> > I worked out the solution but could not replace the results in the split lists.
> >
> > Original dataframe , df1
> >   ID ID_2 Firist Value
> > 1  a   aa   TRUE     2
> > 2  a   ab  FALSE    NA
> > 3  a   ac  FALSE    NA
> > 4  b   aa   TRUE     5
> > 5  b   ab  FALSE    NA
> > Sdf1
> > $a
> > ID ID_2 Firist Value
> > 1  a   aa   TRUE     2
> > 2  a   ab  FALSE    NA
> > 3  a   ac  FALSE    NA
> > $b
> >   ID ID_2 Firist Value
> > 4  b   aa   TRUE     5
> > 5  b   ab  FALSE    NA
> > Desired results
> > ID ID_2 Firist Value
> > 1  a   aa   TRUE    2
> > 2  a   ab  FALSE    2
> > 3  a   ac  FALSE    2
> >
> > $b
> >   ID ID_2 Firist Value
> > 4  b   aa   TRUE     5
> > 5  b   ab  FALSE     5
> >
> > My code
> >
> > sdf <- split(df1,df$ID)
> > lapply(sdf, function(z)
> > ifelse(is.na(z$Value),z$Value[!is.na(z$Value)],z$Value))
> > result:
> > $ a: num [1:3] 2 2 2
> > $ b: num [1:2] 5 5
> >
> > How could I put these two lists back in the split data frame, sdf1?
> > Then I could use do.call to reassemble a data frame from the split
> > lists,
> >
> > Thanks,
> > EK
>
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