[R] Using column length in plot gives error

[MikSmith]

Hi Stephanie

Absolutely right! My CSV was imported as a factor. Reading the R FAQ:

http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-convert-factors-to-numeric_003f

I actually need to do:

as.numeric(as.character(spectra.wavelength))

to get back to my original data.

Many thanks for the pointer

mike



Stephanie Kovalchik wrote:
> 
> Is spectra.wavelength a factor? If so, plot will treat it as  
> categorical and not draw a line. Try the following modification.
> 
> plot(as.numeric(spectra.wavelength), cormat, type = "l", ylim=c(-1,1),  
> xlab="Wavelength (nm)", ylab="Correlation")
> 
> Quoting MikSmith <mike at hsm.org.uk>:
> 
>>
>> Hi
>>
>> I'm trying to write a generic script for processing some data which
>> finishes
>> off with some plots. Given Im never sure how many columns will be in my
>> dataframe I wanted to using the following
>>
>> plot(spectra.wavelength, cormat, type = "l", ylim=c(-1,1),
>> xlab="Wavelength
>> (nm)", ylab="Correlation")
>>
>> however even if I specify as type="l" it appears plot as points (right
>> hand
>> plot). If I specify a range such as
>>
>> plot(650:700, cormat, type = "l", ylim=c(-1,1), xlab="Wavelength (nm)",
>> ylab="Correlation")
>>
>> it looks good (left hand plot). If I try something like:
>>
>> plot(spectra.wavelength[1]:spectra.wavelength[length(spectra.wavelength)],
>> cormat, type = "l", ylim=c(-1,1), xlab="Wavelength (nm)",
>> ylab="Correlation")
>>
>> it fails with "variable lengths differ" and when I look at
>> spectra.wavelength[1] it gives me the value but then states there are 53
>> levels.
>>
>> What does this mean and how can I get the result I want??!
>>
>> many thanks
>>
>> mike http://www.nabble.com/file/p23562717/1.pdf 1.pdf
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>>
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>>
> 
> ______________________________________________
> 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.
> 
> 

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