R help - Jun 2005 - reading csv-data

Hi!

I have had this problem for a long time. I have tried to study the manuals and
search the mailing lists, but I can not solve this. I think there has to be one
simple solution to this, but I just can not find it. 

I have saved the data in excel (csv-format). Then I read the data in R e.g.
>data <- read.csv2("example.csv", header=TRUE)
I look the data and it looks ok. E.g
>data
     Mean1   
1   4.4332  
2   8.5113  
3  35.1624 
4   9.1693 
5    2.974 
6  65.1578 
7  43.2241 
8   3.1278 
9   5.3364 
10  3.9767 

However, this "Mean1" is categorical when it should be real numbers.
> Mean1
[1] 4.4332  8.5113  35.1624 9.1693  2.974   65.1578 43.2241 3.1278  5.3364 
Levels: 2.974 3.1278 35.1624 4.4332 43.2241 5.3364 65.1578 8.5113 9.1693

Why R does not understand that this should be real numbers? What am I doing
wrong here? Thanks for your help.

Regards,
Johanna Sundvik

On Fri, 17 Jun 2005, Johanna Sundvik wrote:
> However, this "Mean1" is categorical when it should be real
numbers.
>
>> Mean1
> [1] 4.4332  8.5113  35.1624 9.1693  2.974   65.1578 43.2241 3.1278  5.3364
> Levels: 2.974 3.1278 35.1624 4.4332 43.2241 5.3364 65.1578 8.5113 9.1693
>
> Why R does not understand that this should be real numbers? What am I doing
> wrong here? Thanks for your help.
>
Your files must have some entries that are not numbers, such as "." or
something.  R then can't tell that the field is supposed to be numeric. 
This may happen with missing data, in which case the na.strings= argument 
can be used to tell R how missing data are specified.

You can convert the data to numeric as described in FAQ 7.10

 	-thomas

In my experience, this has always been due to the presence of 
non-numeric values in the input.

In the example you show, it is not obvious that there is any. I would 
start by first inspecting the input file very carefully, using a text 
editor outside of R. Since your example appears to have only one 
column of data, you could try reading it with the scan() function. 
This might produce additional information that would help you 
identify any non-numeric data. Using count.fields() on the data file 
might reveal something.

If "Mean1" is an element of "data", then simply typing
"Mean1" at the
prompt should produce a "not found" message. Yet Mean1 was found. 
Have you omitted something in your email, or is there another object 
named "Mean1"?

-Don

At 4:50 PM +0300 6/17/05, Johanna Sundvik wrote:
>Hi!
>
>I have had this problem for a long time. I have tried to study the manuals
and
>search the mailing lists, but I can not solve this. I think there 
>has to be one
>simple solution to this, but I just can not find it.
>
>I have saved the data in excel (csv-format). Then I read the data in R e.g.
>
>>data <- read.csv2("example.csv", header=TRUE)
>
>I look the data and it looks ok. E.g
>
>>data
>      Mean1  
>1   4.4332 
>2   8.5113 
>3  35.1624
>4   9.1693
>5    2.974
>6  65.1578
>7  43.2241
>8   3.1278
>9   5.3364
>10  3.9767
>
>However, this "Mean1" is categorical when it should be real
numbers.
>
>>  Mean1
>[1] 4.4332  8.5113  35.1624 9.1693  2.974   65.1578 43.2241 3.1278  5.3364
>Levels: 2.974 3.1278 35.1624 4.4332 43.2241 5.3364 65.1578 8.5113 9.1693
>
>Why R does not understand that this should be real numbers? What am I doing
>wrong here? Thanks for your help.
>
>Regards,
>Johanna Sundvik
>
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-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA