Message-ID: <1353010910.94310.YahooMailNeo@web142602.mail.bf1.yahoo.com>
Date: 2012-11-15T20:21:50Z
From: arun
Subject: using ifelse to remove NA's from specific columns of a data frame containing strings and numbers
In-Reply-To: <1353007792270-4649642.post@n4.nabble.com>
HI,
But, this replace second column NAs to 1.? May be, the na.replace() should be applied to df1[,-1]
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)
df2<-df1[,-1]
na.replace<-seq(1:ncol(df2))-1
df2[,names(df2)]<-sapply(1:dim(df2)[2],function(ii){ifelse(is.na(df2[,ii]),na.replace[ii],df2[,ii])})
df2$col1<-df1$col1
df2[order(names(df2))]
#? 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
A.K.
----- Original Message -----
From: soon yi <soon.yi at ymail.com>
To: r-help at r-project.org
Cc:
Sent: Thursday, November 15, 2012 2:29 PM
Subject: Re: [R] using ifelse to remove NA's from specific columns of a data frame containing strings and numbers
#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]]
>
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