[R] Converting dollar value (factors) to numeric

[Wang, Kevin (SYD)]

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)))
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 
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>>
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>>
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>>
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>
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