[Tutor] What exactly is [::-1]?
rabidpoobear at gmail.com
Thu Jul 26 05:38:37 CEST 2007
> In order to reverse the order of an array, I discovered that I'm
> supposed to use [::-1].
I don't know if 'supposed to' is the correct term.
You could just as easily get away with using ['a','b','c'].reverse().
However, below you're using 'array' and I'm not sure exacly what this is.
Does it have to do with the built-in array module or one of the
> >>> a = array([1., 2., 3.])
> >>> a
> array([ 1., 2., 3.])
> >>> a[::-1]
> array([ 3., 2., 1.])
> I would like to know what exactly the index notation of [::-1] is, where
> it comes from and if there are other variants.
This is called list slicing. Look into it to figure out what all this
I could send you a link but I'd just google 'python list slicing' to
find it, so I'll leave that as an exercise for the reader.
> Thank you for your help. I lurk about on this list and have learned a
> fair bit.
Good to hear :)
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