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Basics of k language and their numpy equivalents

January 4th, 2009 by Adam

Both k language and numpy are array language implementations for numeric-intensive computation. Well, they’re of course more, you can read about them following the links above.

`k`	`numpy`
`+a`	`transpose(a)`
`a+3`	`a+3`
`-a`	`-a`
`a-3`	`a-3`
`*a`	`a[0]`
`a*3`	`a*3`
`a*b`	`a*b`
`%a`	`1./a`
`a%3`	`a/3.`
`&a`	`???`
`a&3`	`where(a<3,a,3)`
`\|a`	`a[::-1]`
`a\|b`	`where(a>b,a,b)`
`4\|a`	`where(a>4,a,4)`
`< a`	`argsort(a)[::-1]`
`a < b`	`a < b`
`>a`	`argsort(a)`
`a>b`	`a>b`
`=a`	`NA (not rectangle result)`
`a=3`	`a==b`
`^a`	`shape(a)`
`a^3`	`a**3`
`!3`	`arange(3)`
`3!a`	`roll(a,3)`
`a!3`	`a%3`
`~a`	`a==0`
`a~b`	`any(a==b)`
`,3`	`array([3])`
`a,b`	`hstack([a,b])`
`#a`	`size(a)`
`3#a`	`resize(a, 3)`
`2 3#a`	`resize(a, [2,3])`
`_ a`	`floor(a)`
`3_ a`	`a[3:]`
`2 3_ a`	`NA (not rectangle result)`
`$a`	`asarray(a,dtype=str)`
`3$a`	`Use standard python formatting`
`?a`	`unique(a)`
`a?3`	`nonzero(a==3)[0][0]`
`@a`	`not ndim(a)`
`a@3`	`a[3]`

And some often used expressions

`a[&a>b]`	`a[a>b]`
`#^a`	`rank(a)`
`(#a)>a?3`	`any(a==3)`
`a[>a]`	`sort(a)`