Converting dollar value (factors) to numeric

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

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

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