R SIG Debian - Nov 2007 - littler usage

Hi,

I've been using r (the little, but sweet one!), and recently found out
about the magic argv vector of the rest of arguments passed to it.  How
can we process an argument that represents elements of a vector:

$ r littler_ex.R 14 '3, 2'
Error in ff * ss : non-numeric argument to binary operator

where:

,-----[ cat ~/scripts/R/littler_ex.R ]
| ff <- as.numeric(argv[1])
| ss <- c(argv[2])
| print(ff * ss)
`-----


Cheers,

-- 
Seb

Seb, 

On 17 November 2007 at 15:16, Sebastian P. Luque wrote:
| Hi,
| 
| I've been using r (the little, but sweet one!), and recently found out

It's also way cuter than the ugly Rscript. But heck, I'm one of the
parents,
so I had to say that :)

| about the magic argv vector of the rest of arguments passed to it.  How
| can we process an argument that represents elements of a vector:
| 
| $ r littler_ex.R 14 '3, 2'
| Error in ff * ss : non-numeric argument to binary operator
| 
| where:
| 
| ,-----[ cat ~/scripts/R/littler_ex.R ]
| | ff <- as.numeric(argv[1])
| | ss <- c(argv[2])
| | print(ff * ss)
| `-----

You're almost there -- just use 'as.numeric' on ss too:

edd at ron:~> cat /tmp/seb.r
#!/usr/bin/env r

ff <- as.numeric(argv[1])
ss <- as.numeric(argv[2])
print(ff * ss)
edd at ron:~> /tmp/seb.r 2 3
[1] 6
edd at ron:~>    

There are a few examples of argv use in the examples directory:

edd at ron:~> grep -c argv /usr/share/doc/littler/examples/*r
/usr/share/doc/littler/examples/fsizes.r:0
/usr/share/doc/littler/examples/install.r:2
/usr/share/doc/littler/examples/mph.r:2
/usr/share/doc/littler/examples/pace.r:3
/usr/share/doc/littler/examples/update.r:0

Hope this helps,  Dirk

-- 
Three out of two people have difficulties with fractions.