R help - Nov 2012 - using ifelse to remove NA's from specific columns of a data frame containing strings and numbers

Hi everyone,

I have a data frame one of whose columns is a character vector and the rest
are numeric, and in debugging a script, I noticed that an ifelse call seems
to be coercing the character column to a numeric column, and producing
unintended values as a result.   Roughly, here's what I tried to do:

df: a data frame with, say, the first column as a character column and the
second and third columns numeric.

also: NA's occur only in the numeric columns, and if they occur in one,
they occur in the other as well.

I wanted to replace the NA's in column 2 with 0's and the ones in column
3
with 1's, so first I did this:
> na.replacements <-ifelse(col(df)==2,0,1).
Then I used a second ifelse call to try to remove the NA's as I wanted,
first by doing this:
> clean.df <- ifelse(is.na(df), na.replacements, df),
which produced a list of lists vaguely resembling df, with the NA's mostly
intact, and so then I tried this:
> clean.df <- ifelse(is.na(df), na.replacements, unlist(df)),
which seems to work if all the columns are numeric, but otherwise changes
strings to numbers.

I can't make sense of the help documentation enough to clear this up, but
my guess is that the "yes" and "no" values passed to ifelse
need to be
vectors, in which case it seems I'll have to use another approach entirely,
but even if is not the case and lists are acceptable, I'm not sure how to
convert a mixed-mode data frame into a vector-like list of elements (which
I would hope would work).

I'd be grateful for any suggestions!

Thanks,
David Romano

	[[alternative HTML version deleted]]

Hi everyone, please put me off that list!!! The unsubscribe function does not
function...
THANKS!!!
BW Sonja

-----Urspr?ngliche Nachricht-----
Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
Auftrag von David Romano
Gesendet: 15 November 2012 12:19
An: r-help at r-project.org
Betreff: [R] using ifelse to remove NA's from specific columns of a data
frame containing strings and numbers

Hi everyone,

I have a data frame one of whose columns is a character vector and the rest are
numeric, and in debugging a script, I noticed that an ifelse call seems to be
coercing the character column to a numeric column, and producing
unintended values as a result.   Roughly, here's what I tried to do:

df: a data frame with, say, the first column as a character column and the
second and third columns numeric.

also: NA's occur only in the numeric columns, and if they occur in one, they
occur in the other as well.

I wanted to replace the NA's in column 2 with 0's and the ones in column
3 with 1's, so first I did this:
> na.replacements <-ifelse(col(df)==2,0,1).
Then I used a second ifelse call to try to remove the NA's as I wanted,
first by doing this:
> clean.df <- ifelse(is.na(df), na.replacements, df),
which produced a list of lists vaguely resembling df, with the NA's mostly
intact, and so then I tried this:
> clean.df <- ifelse(is.na(df), na.replacements, unlist(df)),
which seems to work if all the columns are numeric, but otherwise changes
strings to numbers.

I can't make sense of the help documentation enough to clear this up, but my
guess is that the "yes" and "no" values passed to ifelse
need to be vectors, in which case it seems I'll have to use another approach
entirely, but even if is not the case and lists are acceptable, I'm not sure
how to convert a mixed-mode data frame into a vector-like list of elements
(which I would hope would work).

I'd be grateful for any suggestions!

Thanks,
David Romano

	[[alternative HTML version deleted]]

______________________________________________
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.

David:

You seem to be getting lost in basic R tasks. Have you read the Intro
to R tutorial? If not, do so, as this should tell you how to do what
you need. If so, re-read the sections on indexing ("["), replacement,
and NA's. Also read about character vectors and factors.

-- Bert

On Thu, Nov 15, 2012 at 3:19 AM, David Romano <dromano at stanford.edu>
wrote:
> Hi everyone,
>
> I have a data frame one of whose columns is a character vector and the rest
> are numeric, and in debugging a script, I noticed that an ifelse call seems
> to be coercing the character column to a numeric column, and producing
> unintended values as a result.   Roughly, here's what I tried to do:
>
> df: a data frame with, say, the first column as a character column and the
> second and third columns numeric.
>
> also: NA's occur only in the numeric columns, and if they occur in one,
> they occur in the other as well.
>
> I wanted to replace the NA's in column 2 with 0's and the ones in
column 3
> with 1's, so first I did this:
>
>> na.replacements <-ifelse(col(df)==2,0,1).
>
> Then I used a second ifelse call to try to remove the NA's as I wanted,
> first by doing this:
>
>> clean.df <- ifelse(is.na(df), na.replacements, df),
>
> which produced a list of lists vaguely resembling df, with the NA's
mostly
> intact, and so then I tried this:
>
>> clean.df <- ifelse(is.na(df), na.replacements, unlist(df)),
>
> which seems to work if all the columns are numeric, but otherwise changes
> strings to numbers.
>
> I can't make sense of the help documentation enough to clear this up,
but
> my guess is that the "yes" and "no" values passed to
ifelse need to be
> vectors, in which case it seems I'll have to use another approach
entirely,
> but even if is not the case and lists are acceptable, I'm not sure how
to
> convert a mixed-mode data frame into a vector-like list of elements (which
> I would hope would work).
>
> I'd be grateful for any suggestions!
>
> Thanks,
> David Romano
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> 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.


-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm

Hi,

df1<-read.table(text="
col1 col2 col3
A?? 15.5?? 8.5
A?? 8.5??? 7.5
A?? NA???? NA
B?? 8.0?? 6.0
B?? NA???? NA
B?? 9.0?? 10.0
",sep="",header=TRUE,stringsAsFactors=FALSE)
?str(df1)
#'data.frame':??? 6 obs. of? 3 variables:
# $ col1: chr? "A" "A" "A" "B" ...
# $ col2: num? 15.5 8.5 NA 8 NA 9
# $ col3: num? 8.5 7.5 NA 6 NA 10

?df1$col2[is.na(df1$col2)]<-0
?df1$col3[is.na(df1$col3)]<-1
?df1
#? col1 col2 col3
#1??? A 15.5? 8.5
#2??? A? 8.5? 7.5
#3??? A? 0.0? 1.0
#4??? B? 8.0? 6.0
#5??? B? 0.0? 1.0
#6??? B? 9.0 10.0

#or if you want to use ifelse() from the original df1

?ifelse(is.na(df1$col2),0,df1$col2)
#[1] 15.5? 8.5? 0.0? 8.0? 0.0? 9.0
?ifelse(is.na(df1$col3),1,df1$col2)
#[1] 15.5? 8.5? 1.0? 8.0? 1.0? 9.0
A.K.




----- Original Message -----
From: David Romano <dromano at stanford.edu>
To: r-help at r-project.org
Cc: 
Sent: Thursday, November 15, 2012 6:19 AM
Subject: [R] using ifelse to remove NA's from specific columns of a data
frame containing strings and numbers

Hi everyone,

I have a data frame one of whose columns is a character vector and the rest
are numeric, and in debugging a script, I noticed that an ifelse call seems
to be coercing the character column to a numeric column, and producing
unintended values as a result.?  Roughly, here's what I tried to do:

df: a data frame with, say, the first column as a character column and the
second and third columns numeric.

also: NA's occur only in the numeric columns, and if they occur in one,
they occur in the other as well.

I wanted to replace the NA's in column 2 with 0's and the ones in column
3
with 1's, so first I did this:
> na.replacements <-ifelse(col(df)==2,0,1).
Then I used a second ifelse call to try to remove the NA's as I wanted,
first by doing this:
> clean.df <- ifelse(is.na(df), na.replacements, df),
which produced a list of lists vaguely resembling df, with the NA's mostly
intact, and so then I tried this:
> clean.df <- ifelse(is.na(df), na.replacements, unlist(df)),
which seems to work if all the columns are numeric, but otherwise changes
strings to numbers.

I can't make sense of the help documentation enough to clear this up, but
my guess is that the "yes" and "no" values passed to ifelse
need to be
vectors, in which case it seems I'll have to use another approach entirely,
but even if is not the case and lists are acceptable, I'm not sure how to
convert a mixed-mode data frame into a vector-like list of elements (which
I would hope would work).

I'd be grateful for any suggestions!

Thanks,
David Romano

??? [[alternative HTML version deleted]]

______________________________________________
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.

#Data
df<-data.frame(id=letters[1:10],var1=rnorm(10,10,5),var2=rnorm(10,5,2),var3=rnorm(10,1,1))
#Missing
df$var1[2]<-df$var2[c(2,6)]<-df$var3[c(2,5)]<-NA

na.replace<-seq(1:ncol(df))-1

df[,names(df)]<-sapply(1:dim(df)[2], function(ii)
{ifelse(is.na(df[,ii]),na.replace[ii],df[,ii])} )




David Romano-2 wrote
> Hi everyone,
> 
> I have a data frame one of whose columns is a character vector and the
> rest
> are numeric, and in debugging a script, I noticed that an ifelse call
> seems
> to be coercing the character column to a numeric column, and producing
> unintended values as a result.   Roughly, here's what I tried to do:
> 
> df: a data frame with, say, the first column as a character column and the
> second and third columns numeric.
> 
> also: NA's occur only in the numeric columns, and if they occur in one,
> they occur in the other as well.
> 
> I wanted to replace the NA's in column 2 with 0's and the ones in
column 3
> with 1's, so first I did this:
> 
>> na.replacements <-ifelse(col(df)==2,0,1).
> 
> Then I used a second ifelse call to try to remove the NA's as I wanted,
> first by doing this:
> 
>> clean.df <- ifelse(is.na(df), na.replacements, df),
> 
> which produced a list of lists vaguely resembling df, with the NA's
mostly
> intact, and so then I tried this:
> 
>> clean.df <- ifelse(is.na(df), na.replacements, unlist(df)),
> 
> which seems to work if all the columns are numeric, but otherwise changes
> strings to numbers.
> 
> I can't make sense of the help documentation enough to clear this up,
but
> my guess is that the "yes" and "no" values passed to
ifelse need to be
> vectors, in which case it seems I'll have to use another approach
> entirely,
> but even if is not the case and lists are acceptable, I'm not sure how
to
> convert a mixed-mode data frame into a vector-like list of elements (which
> I would hope would work).
> 
> I'd be grateful for any suggestions!
> 
> Thanks,
> David Romano
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help@
>  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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