Message-ID: <48CFC3A8.7020108@comcast.net>
Date: 2008-09-16T14:33:12Z
From: Marc Schwartz
Subject: HI
In-Reply-To: <OF5C84429F.5A43D7CF-ON802574C6.004E0760-802574C6.004E8321@hsl.gov.uk>
on 09/16/2008 09:20 AM Richard.Cotton at hsl.gov.uk wrote:
>>> Does anyone know an easy way to convert all the zero values in a
>> imported csv table into NA's
>>
>> Depends on the data structure you gave your imported table. In a
>> single numeric vector (named, say, vec), the syntax is
>>
>> is.na(vec[vec==0]) <- TRUE
>
> That throws errors for me. An alternative is
> vec[vec==0] <- NA
>
> This also works for data frames, e.g.
> df <- data.frame(a=c(1,2,3,0,3,4,0,5,2), b=c(1,0,0,1,1,0,1,1,0))
> df[df==0] <- NA
>
The correct syntax using is.na() would be:
> df
a b
1 1 1
2 2 0
3 3 0
4 0 1
5 3 1
6 4 0
7 0 1
8 5 1
9 2 0
is.na(df) <- df == 0
> df
a b
1 1 1
2 2 NA
3 3 NA
4 NA 1
5 3 1
6 4 NA
7 NA 1
8 5 1
9 2 NA
Review ?is.na for correct use.
HTH,
Marc Schwartz