[R] regex find anything which is not a number

[Steve Taylor]

How about letting a standard function decide which are numbers:

which(!is.na(suppressWarnings(as.numeric(myvector))))

Also works with numbers in scientific notation and (presumably) different decimal characters, e.g. comma if that's what the locale uses.


-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Adrian Du?a
Sent: Thursday, 12 March 2015 8:27a
To: r-help at r-project.org
Subject: [R] regex find anything which is not a number

Hi everyone,

I need a regular expression to find those positions in a character
vector which contain something which is not a number (either positive
or negative, having decimals or not).

myvector <- c("a3", "N.A", "1.2", "-3", "3-2", "2.")

In this vector, only positions 3 and 4 are numbers, the rest should be captured.
So far I am able to detect anything which is not a number, excluding - and .

> grep("[^-0-9.]", myvector)
[1] 1 2

I still need to capture positions 5 and 6, which in human language
would mean to detect anything which contains a "-" or a "." anywhere
else except at the beginning of a number.

Thanks very much in advance,
Adrian


-- 
Adrian Dusa
University of Bucharest
Romanian Social Data Archive
Soseaua Panduri nr.90
050663 Bucharest sector 5
Romania

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