[R] Convert factor to "double"?

[Uwe Ligges]

p.silva at gmx.net wrote:
> Hi!
> 
> I'm reading a tab-seperated CVS file with:
> test1 <- read.table("data.txt", header=TRUE)
> 
> It's in the following format:
> 
> Date_Time qK qL vL vP  ...
> 0         30 22 110 88 ...
> ...
> 
> (BTW: It seems to me R shifts the column descriptions by one.)

No, look into your data file first.


> Anyway, I would like to Fourier-transform one column. So I say:
>> fft(test1$vP)
> Error in levels(x)[x] : invalid subscript type 'complex'
> 
> I guess this is some typing error but I don't know which function I have to use for conversion.
> 
> Some more Info about the data:
> 
>> test1$vP[1:10]
>  [1] 110 108 116 118 114 120 117 111 95  118
> 166 Levels: - 0 1 10 100 101 102 103 104 105 106 107 108 109 11 110 111 ... 99


Obviously there is some "-" sign in your data file. You might want to 
fix that prior to importing the data. You cannot convert easily to 
numeric with artifacts like the string "-" in your data.

Uwe Ligges


>> class( test1$vPkw)
> [1] "factor"
> 
> 
> I would appreciate any hints! Thanks in advance!
> 
> Best, Philip
> --
> 
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