[19077] in s-news-athena
Re: [S] Putting values into matrices: desired behaviour?
daemon@ATHENA.MIT.EDU (Martin Maechler)
Wed Sep 1 03:35:40 1999
Date: Wed, 1 Sep 1999 09:30:01 +0200
Message-Id: <199909010730.JAA02696@sophie.ethz.ch>
From: Martin Maechler <maechler@stat.math.ethz.ch>
To: Mette.Langaas@nr.no
Cc: s-news@wubios.wustl.edu, R-help@stat.math.ethz.ch
In-Reply-To: <37CCC8DE.A756F3D6@nr.no> (message from Mette Langaas on Wed, 01
Sep 1999 08:34:06 +0200)
Reply-To: Martin Maechler <maechler@stat.math.ethz.ch>
>>>>> On Wed, 01 Sep 1999 08:34, Mette Langaas <Mette.Langaas@nr.no> said:
Mette> I'm running S-Plus 5.1 on UNIX (but the same behaviour I'm
Mette> describing is seen on S-Plus 3.4 R1 for UNIX).
Mette> I have first created a matrix with two rows and three columns
>> test_matrix(ncol=3,nrow=2)
>> test
Mette> [,1] [,2] [,3]
Mette> [1,] NA NA NA
Mette> [2,] NA NA NA
Mette> I then want to put values into parts of the matrix, but by mistake I
Mette> index outside the matrix (use rows 3-7 when there are only 2 rows).
>> ind_matrix(c(1,2,3,4,5,6,7,2,2,2,2,2,2,2),ncol=2)
>> ind
Mette> [,1] [,2]
Mette> [1,] 1 2
Mette> [2,] 2 2
Mette> [3,] 3 2
Mette> [4,] 4 2
Mette> [5,] 5 2
Mette> [6,] 6 2
Mette> [7,] 7 2
>> test[ind]_c(3,4,5,6,7,8,9)
>> test
Mette> [,1] [,2] [,3]
Mette> [1,] NA 3 5
Mette> [2,] NA 4 6
Mette> The first observation is that in addition to correctly putting
Mette> values 3 ang 4 into position (1,2) and (2,2) the value 5 is put
Mette> into (1,3) instead of (3,2) as requested and
Mette> 6 is put into (2,3) instead of (4,3) as requested.
<...snip...>
Mette> Is this the desired behaviour of indexing matrices? What
Mette> measures can I take to avoid this behaviour -- e.g. to instead
Mette> get an error message?
In R, you do get an error message
``Error: subscript out of bounds''
and test[,] remains unaltered.
I hope nobody complains about non-compatibility with S... ;-)
Martin Maechler <maechler@stat.math.ethz.ch> http://stat.ethz.ch/~maechler/
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