[Numpy-discussion] Outer join ?
Wed Feb 11 23:40:59 CST 2009
On Wed, Feb 11, 2009 at 23:24, A B <email@example.com> wrote:
> I have the following data structure:
> col1 | col2 | col3
> For each key in the second column, I would like to create an array
> where for all unique values in the first column, there will be either
> a value or zero if there is no data available. Like so:
> # 20080101, 20080201, 20080301, 20080601
> key1 - 4, 6, 5, 0
> key2 - 0, 0, 3.4, 5.6
> Ideally, the results would end up in a 2d array.
> What's the most efficient way to accomplish this? Currently, I am
> getting a list of uniq col1 and col2 values into separate variables,
> then looping through each unique value in col2
> a = loadtxt(...)
> dates = unique(a[:]['col1'])
> keys = unique(a[:]['col2'])
> for key in keys:
> b = a[where(a[:]['col2'] == key)]
Take a look at setmember1d().
"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
-- Umberto Eco
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