Re: [R] Error in Arules

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Tue, 04 Mar 2008 18:34:41 -0500

On 3/4/2008 5:14 PM, Tibert, Brock wrote:
> Thanks for getting back to me.
>
> Here are the basic commands:
>
> These commands work:
> library("arules")
> basket <- read.csv("C:/Documents and Settings/ /Desktop/mba2.csv",
> na.strings=c(".", "NA", "", "?"))
> basket2 <- as(split(basket$Product, basket$Id), "transactions")
>
> the following command used to work. It stopped when I tried to edit the
> axes.
> image(basket2)
>
> Here is the error:
> Error in image.default(basket2) : 'z' must be a matrix

basket2 is not a matrix. I think the business about the axes is a coincidence: probably the previous times when you tried this, basket2 *was* a matrix.

>
> As an aside, when I start R, I noticed that this shows up, and I do not
> remember if this was normal:
>
> *******
> Loading required package: utils
> Loading required package: stats
> Loading required package: lattice
>
> Attaching package: 'Matrix'
>
>
> The following object(s) are masked from package:stats :
>
> xtabs
>
> ** fixing ngCMatrix validation
> [Previously saved workspace restored]

Some people disagree, but in my opinion, it's always a bad idea to save your workspace, so that R restores old one when you restart. You never know what is in there causing trouble.

My advice would be to always choose "No" when asked whether to save the workspace as you shut down. Then, while R is shut down, find the .RData file (probably in your home directory) and delete it. Be aware that this will lose all R objects in it, so don't do it unless you know how to rebuild them.

Duncan Murdoch

> ********
>
>
> Thanks again,
>
> Brock
>
> -----Original Message-----
> From: Duncan Murdoch [mailto:murdoch_at_stats.uwo.ca]
> Sent: Tuesday, March 04, 2008 4:51 PM
> To: Tibert, Brock
> Cc: r-help_at_r-project.org
> Subject: Re: [R] Error in Arules
>
> On 04/03/2008 4:34 PM, Tibert, Brock wrote:

>> Hi everyone,
>> 
>>  
>> 
>> This is my first posting and I am just starting to fumble my way thru

> R.
>> I have been working thru the Arules package, and I used to be able to
>> use the image function and I get the following message:
>> 
>>  
>> 
>> Error in image.default(basket2) : 'z' must be a matrix
>> 
>>  
>> 
>> I used to be able to plot the image.  I only started to get this error
>> when I tried to add x and y axis labels.  Any ideas?

>
> It would be helpful to show code that works, and code that doesn't. But
>
> what the error message says is that someone (you? the code you called?)
>
> called the image.default function with just one argument basket2, and
> it's not a matrix.
>
> Duncan Murdoch


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