R frustration of the day

Whenever you take a 1 column slice of a matrix, that gets automatically converted into a vector. But if you take a slice of several columns, it remains a matrix. The problem is you don’t always know in advance how big the slice will be, so if you do this:

You'll get an error if x is 1. This creates the worst kind of bug: an intermittent one that will hide until the right (wrong?) value of x occurs. To fix the problem you need to RE-declare the slice to be a matrix with ncol=x after you take the slice.

This entry was posted on Sunday, April 11th, 2010 at 8:39 pm and is filed under feature, r. You can follow any comments to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

2 comments

  2. admin
    May 3, 2010 at 5:04 pm

    Hi Stu,

    Thanks for the link. I didn’t know about the

    drop=F

    option.

    Every programming language has it’s quirks and hidden bogies, but R seems to have more than its fair share, a situation made worse by the documentation (something I’ll write more about in a future post).

    Cheers,

    Matt