[R] Understanding cenros Error

[Jim Lemon]

On 07/11/2012 05:54 AM, Rich Shepard wrote:
> Before reading water chemistry into a data frame I removed all missing
> data. Yet when I try to run cenros() to summarize a specific chemical I get
> an error that I do not understand:
>
> with( subset(chem, param=='Ag'), cenros(quant,ceneq1) )
> Error in lm.fit(x, y, offset = offset, singular.ok = singular.ok, ...) :
> NA/NaN/Inf in 'y'
>
> I would like to learn what I did incorrectly so I can avoid these errors
> in the future.
>
> The data frame structure is
>
> str(chem)
> 'data.frame': 120309 obs. of 8 variables:
> $ site : Factor w/ 65 levels ";Influent","D-1",..: 2 2 2 2 2 2 ...
> $ sampdate: Date, format: "2007-12-12" "2007-12-12" ...
> $ preeq0 : logi TRUE TRUE TRUE TRUE TRUE TRUE ...
> $ param : Factor w/ 37 levels "Ag","Al","Alk_tot",..: 1 2 8 17 3 9 ...
> $ quant : num 0 0.106 1 231 231 0.011 0 0.002 0 100 ...
> $ ceneq1 : logi FALSE FALSE TRUE FALSE FALSE FALSE ...
> $ floor : num 0 0.106 0 231 231 0.011 0 0 0 100 ...
> $ ceiling : Factor w/ 3909 levels "0.000","0.000)",..: 1 116 841 1771 ...
>
> I ran dput() on the data frame but cannot make sense of the output (a 5.5M
> ASCII text file).
>
Hi Rich,
I don't have the NADA package, but I suspect that the cenros function is 
doing something like dividing by zero. With that much data, it may be 
hard to pinpoint where this is occurring. I would cut my data in half, 
run it, cut the remainder in half, run it and so on until the error goes 
away. With any luck, the last slice of data that was removed won't be 
too large to work out which value is causing the problem and what the 
problem is.

Jim