[R] regex find anything which is not a number

[Adrian Dușa]

Perfect, perfect, perfect.
Thanks very much, John.
Adrian

On Wed, Mar 11, 2015 at 10:00 PM, John McKown
<john.archie.mckown at gmail.com> wrote:
> See if the following will work for you:
>
> grep('^-?[0-9]+([.]?[0-9]+)?$',myvector,perl=TRUE,invert=TRUE)
>
>> myvector <- c("a3", "N.A", "1.2", "-3", "3-2", "2.")
>> grep('^-?[0-9]+([.][0-9]+)?$',myvector,perl=TRUE,invert=TRUE)
> [1] 1 2 5 6
>>
>
> The key is to match a number, and then invert the TRUE / FALSE (invert=TRUE).
> ^ == start of string
> -? == 0 or 1 minus signs
> [0-9]+ == one or more digits
>
> optionally followed by the following via use of (...)?
> [.] == an actual period. I tried to escape this, but it failed
> [0-9]+ == followed by one or more digits
>
> $ == followed by the end of the string.
>
> so: optional minus, followed by one or more digits, optionally
> followed by (a period with one or more ending digits).
>
>
> On Wed, Mar 11, 2015 at 2:27 PM, Adrian Dușa <dusa.adrian at unibuc.ro> wrote:
>> 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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>> and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
> He's about as useful as a wax frying pan.
>
> 10 to the 12th power microphones = 1 Megaphone
>
> Maranatha! <><
> John McKown



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