[R] find numbers in a line with letters
Bert Gunter
gunter.berton at gene.com
Thu Aug 27 01:19:25 CEST 2009
Re-using Gabor's suggestion from yesterday, I think the regex incantation
gsub("[^[:digit:].]+"," ",x)
also will do, where x is a your vector of strings. It says to replace runs
of everything but digits and . with a single space.
> x
[1] "this Item costs 3.32 Dollars or maybe 10.00 cents"
> gsub("[^[:digit:].]+"," ",x)
[1] " 3.32 10.00 "
You can then "pipe" this through a textConnection to convert it to numeric:
> scan(textConnection(gsub("[^[:digit:].]+"," ",x)))
Read 2 items
[1] 3.32 10.00
Bert Gunter
Genentech Nonclinical Biostatisics
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of Steve Lianoglou
Sent: Wednesday, August 26, 2009 3:49 PM
To: Martin Batholdy
Cc: r-help at r-project.org
Subject: Re: [R] find numbers in a line with letters
Hi,
On Aug 26, 2009, at 6:38 PM, Martin Batholdy wrote:
> hi,
>
> is there an easy way to extract numbers from a string?
>
> for example I have;
> "this Item costs 3.32 Dollars"
>
> is there an easy way to extract the 3.32 as a number?
Regular expressions to the rescue?
Perhaps you'll need to fine tune it, but see here:
R> gregexpr("(\\d+(\\.\\d+)?)", "this Item costs 3.32 Dollars", perl=T)
[[1]]
[1] 17
attr(,"match.length")
[1] 4
R> gregexpr("(\\d+(\\.\\d+)?)", "this Item costs 3.32 Dollars, that
item costs 10.12 dollars", perl=T)
[[1]]
[1] 17 47
attr(,"match.length")
[1] 4 5
R> gregexpr("(\\d+(\\.\\d+)?)", "this Item costs 3.32 Dollars, that
item costs 10 dollars even, ", perl=T)
[[1]]
[1] 17 47
attr(,"match.length")
[1] 4 2
R> gregexpr("(\\d+(\\.\\d+)?)", "this one is free ", perl=T)
[[1]]
[1] -1
attr(,"match.length")
[1] -1
HTH,
-steve
--
Steve Lianoglou
Graduate Student: Computational Systems Biology
| Memorial Sloan-Kettering Cancer Center
| Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact
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