[R] Converting dollar value (factors) to numeric

[David Winsemius]

On May 5, 2010, at 11:31 PM, Wang, Kevin (SYD) wrote:

> Hi Phil and all those who replied,
>
> Thanks heap!  Yes it worked to a certain extent.  However, if I have  
> the
> following case:
>> x <- c("$135,359.00", "$135359.00", "$1,135,359.00")
>> y <- sub('\\$','',as.character(x))
>> cost <- as.numeric(sub('\\,','',as.character(y)))

Try gsub, it seems to be more "greedy" :

cost <- as.numeric(gsub('\\,','',as.character(y)))

-- 
David
> Warning message:
> NAs introduced by coercion
>> cost
> [1] 135359 135359     NA
>
> Then the third value bcomes NA -- though I suspect it's probably has
> something to do with regular expression (which I'm not sure how to  
> fix)
> than R?
>
> Thanks again for the help!
>
> Cheers
> Kev
>
> -----Original Message-----
> From: Phil Spector [mailto:spector at stat.berkeley.edu]
> Sent: Wednesday, 5 May 2010 6:14 PM
> To: Wang, Kevin (SYD)
> Cc: r-help at r-project.org
> Subject: Re: [R] Converting dollar value (factors) to numeric
>
> Kev-
>   The most reliable way to do the conversion is as follows:
>
>> x = factor(c('$112.11','$119.15','$121.32'))
>> as.numeric(sub('\\$','',as.character(x)))
> [1] 112.11 119.15 121.32
>
> This way negative quantities and numbers without dollar signs are
> handled correctly.  There's certainly no need to create a new input
> file.
>
> It may be easier to understand as
>
> as.numeric(sub('$','',as.character(x),fixed=TRUE))
>
> which gives the same result.
> 					- Phil Spector
> 					 Statistical Computing Facility
> 					 Department of Statistics
> 					 UC Berkeley
> 					 spector at stat.berkeley.edu
>
>
> On Wed, 5 May 2010, Wang, Kevin (SYD) wrote:
>
>> Hi,
>>
>> I'm trying to read in a bunch of CSV files into R where many columns
>> are coded like $111.11.  When reading them in they are treated as
> factors.
>>
>> I'm wondering if there is an easy way to convert them into numeric in
>> R (as I don't want to modify the source data)?  I've done some
>> searches and can't seem to find an easy way to do this.
>>
>> I apologise if this is a trivial question, I haven't been using R for
>> a while.
>>
>> Many thanks in advance!
>>
>> Cheers
>>
>> Kev
>>
>> Kevin Wang
>>> Senior Advisor, Health and Human Services Practice Government
>>> Advisory Services
>>>
>>> KPMG
>>> 10 Shelley Street
>>> Sydney  NSW  2000  Australia
>>>
>>> Tel 	+61 2 9335 8282
>>> Fax	+61 2 9335 7001
>>>
>> kevinwang at kpmg.com.au
>>
>>> Protect the environment: think before you print
>>>
>>>
>>
>>
>> 	[[alternative HTML version deleted]]
>>
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>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT