R help - Nov 2007 - Problem with a non-factor, non-numeric variable in a data.frame

Dear R list,

I would like to perform an ANOVA in a set of measurements, but I have
problems formatting the data.

The data is a two dimensional array containing two columns:
- "Stim" : the type of stimulation (string)
- "Ratio" : a ratio of two numeric values

Now, because some values are missing in the data (defaulting to zero),
part of this array will be populated with NA ratios. Maybe this is
important later.

In order to make the ANOVA analysis, I need to turn my vector into a data.frame.

I tried vector.table=as.data.frame(vector)

But I realized that
is.numeric(Ratio) gives FALSE
is.factor(Ratio) gives TRUE

After reading the documentation, I tried

vector.table=as.data.frame(vector, stringsAsFactors = FALSE)

This time

is.numeric(Ratio) gives FALSE
is.factor(Ratio) gives FALSE

So I don't even know what is Ratio, but it's not yet numeric (is this
due to the NA values?).

How can I get R to understand that Ratio is numeric? Checking the
documentation it seems you can do it with I(x), but the details are
not explained. I also tried as.numeric(Ratio), and everything was
turned into zeros.

Any suggestions?

Cheers,

Alexandre Santos

Neuro-MPI, Martinsread, Germany

Have a look at the R-FAQ issue 7.10.   It's a standard
problem

For more information about your variable try

str(variable).


--- Alexandre Santos <alexandre.santos at ochipepe.org>
wrote:
> Dear R list,
> 
> I would like to perform an ANOVA in a set of
> measurements, but I have
> problems formatting the data.
> 
> The data is a two dimensional array containing two
> columns:
> - "Stim" : the type of stimulation (string)
> - "Ratio" : a ratio of two numeric values
> 
> Now, because some values are missing in the data
> (defaulting to zero),
> part of this array will be populated with NA ratios.
> Maybe this is
> important later.
> 
> In order to make the ANOVA analysis, I need to turn
> my vector into a data.frame.
> 
> I tried vector.table=as.data.frame(vector)
> 
> But I realized that
> is.numeric(Ratio) gives FALSE
> is.factor(Ratio) gives TRUE
> 
> After reading the documentation, I tried
> 
> vector.table=as.data.frame(vector, stringsAsFactors
> = FALSE)
> 
> This time
> 
> is.numeric(Ratio) gives FALSE
> is.factor(Ratio) gives FALSE
> 
> So I don't even know what is Ratio, but it's not yet
> numeric (is this
> due to the NA values?).
> 
> How can I get R to understand that Ratio is numeric?
> Checking the
> documentation it seems you can do it with I(x), but
> the details are
> not explained. I also tried as.numeric(Ratio), and
> everything was
> turned into zeros.
> 
> Any suggestions?
> 
> Cheers,
> 
> Alexandre Santos
> 
> Neuro-MPI, Martinsread, Germany
> 
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