[R] Error when using anova(lm())

[Alison Callahan]

See below.

On Fri, Oct 8, 2010 at 1:01 PM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Oct 8, 2010, at 12:46 PM, Alison Callahan wrote:
>
>> Hello all,
>>
>> I am trying to perform an ANOVA on some data in a data frame, but when
>> I try to use lm(), I get the following error:
>>
>> Error in storage.mode(y) <- "double" :
>>  invalid to change the storage mode of a factor
>> In addition: Warning message:
>> In model.response(mf, "numeric") :
>>  using type="numeric" with a factor response will be ignored
>>
>> Here is a subset of my data:
>>
>>  island_id     refseq_better     total        refseq_proportion
>> fiveprime   threeprime        island_size
>>      1a            29                  57          0.508771929824561
>>   11127     201378               190251
>>      1c            27                  90               0.3
>>            6303879    6600994            297115
>>      1d            33                 115         0.28695652173913
>>  7001283    7421591            420308
>>      2b            11                  42          0.261904761904762
>>  4381375    4520137            138762
>>      2d            27                  81          0.333333333333333
>>  5203929    5497271            293342
>>      3a            44                 141         0.312056737588652
>>  28792      552044              523252
>>
>> When I use sapply(dataframe,mode) to check the modes of the columns,
>> this is my output:
>>
>>      island_id     refseq_better             total
>>  refseq_proportion
>>       "numeric"         "numeric"         "numeric"         "numeric"
>>       fiveprime        threeprime       island_size
>>       "numeric"         "numeric"         "numeric"
>
> So?
>
>> mode(factor(1:10))
> [1] "numeric"
>
> Storage mode is not the right question. "class" is the correct question.
> Best would be to try is.factor()

Looking at the error message, the problem does appear to be with
storage mode ... is this affected by whether the variables are
factors? Note this part of the error:

Error in storage.mode(y) <- "double" :
invalid to change the storage mode of a factor

>
>
>> How do I need to change the format of my data frame so that I do not
>> get the above error?
>
> Figure out which of your columns are factors and apply the FAQ 7.12
>
> --
> David.
>>
>> Thanks!
>>
>> Alison Callahan
>> PhD candidate
>
>
> David Winsemius, MD
> West Hartford, CT
>
>
Thanks,

Alison