R help - Jul 2011 - converting factor to numeric gives "NAs introduced by coercion"

Hi,

I have a dataframe that I imported from a .txt file by:

skogTemp <- read.delim2("Skogaryd_shoot_data.txt", header=TRUE,
fill=TRUE)

and the data are factors, how can avoid factors from the beginning? Although
the file contains both characters and numbers.

I tried to convert some of the columns from factor to numeric and as I
understood it you can not use only as.numeric but as.character first. I got
this warning message:
> skogTemp_1 <- as.numeric(as.character(skogTemp_1[,2:4]))
Warning message:
NAs introduced by coercion 

I have lots of NAs in my data. Tries to check what class I had now but
another warning is given me:
> class(skogTemp_1[,2])
Error in skogTemp_1[, 2] : incorrect number of
dimensions
> class(skogTemp_1[1,2])
Error in skogTemp_1[1, 2] : incorrect number of dimensions

frustrating... I don't know what this mean.

Can anyone help?

Thank you,
Angelica



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Hi:

The argument stringsAsFactors = FALSE will suppress character data
from being converted to factors. For more control, see the arguments
colClasses and as.is in ?read.table - they should carry over to
read.delim[2] but don't quote me on that :)

HTH,
Dennis

On Fri, Jul 29, 2011 at 1:45 AM, anglor <angelica.ekenstam at dpes.gu.se>
wrote:
> Hi,
>
> I have a dataframe that I imported from a .txt file by:
>
> skogTemp <- read.delim2("Skogaryd_shoot_data.txt",
header=TRUE, fill=TRUE)
>
> and the data are factors, how can avoid factors from the beginning?
Although
> the file contains both characters and numbers.
>
> I tried to convert some of the columns from factor to numeric and as I
> understood it you can not use only as.numeric but as.character first. I got
> this warning message:
>
>> skogTemp_1 <- as.numeric(as.character(skogTemp_1[,2:4]))
> Warning message:
> NAs introduced by coercion
>
> I have lots of NAs in my data. Tries to check what class I had now but
> another warning is given me:
>> class(skogTemp_1[,2])
> Error in skogTemp_1[, 2] : incorrect number of dimensions
>> class(skogTemp_1[1,2])
> Error in skogTemp_1[1, 2] : incorrect number of dimensions
>
> frustrating... I don't know what this mean.
>
> Can anyone help?
>
> Thank you,
> Angelica
>
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/converting-factor-to-numeric-gives-NAs-introduced-by-coercion-tp3703408p3703408.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
>

Hi
> Hi,
> 
> I have a dataframe that I imported from a .txt file by:
> 
> skogTemp <- read.delim2("Skogaryd_shoot_data.txt",
header=TRUE,
fill=TRUE)
> 
> and the data are factors, how can avoid factors from the beginning? 
Although
> the file contains both characters and numbers.
You have got an answer but here are some comments. If you have characters 
and numbers in one column the character values are converted to NA by 
as.numeric
> 
> I tried to convert some of the columns from factor to numeric and as I
> understood it you can not use only as.numeric but as.character first. I 
got
> this warning message:
> 
> > skogTemp_1 <- as.numeric(as.character(skogTemp_1[,2:4]))
> Warning message:
> NAs introduced by coercion 
What is skogTemp_1? I presume skogTemp is data frame and in that case you 
can not use such construction directly.
> 
> I have lots of NAs in my data. Tries to check what class I had now but
> another warning is given me:
> > class(skogTemp_1[,2])

skogTemp_1 is probably a vector with only one dimension therefore you get 
this error.
class(skogTemp_1)

shall give you the desired result, however I prefer 

?str

Regards
Petr
> Error in skogTemp_1[, 2] : incorrect number of dimensions
> > class(skogTemp_1[1,2])
> Error in skogTemp_1[1, 2] : incorrect number of dimensions
> 
> frustrating... I don't know what this mean.
> 
> Can anyone help?
> 
> Thank you,
> Angelica
> 
> 
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/converting-
> 
factor-to-numeric-gives-NAs-introduced-by-coercion-tp3703408p3703408.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> 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.