[Numpy-discussion] Outer join ?

A B python6009@gmail....
Wed Feb 11 23:24:39 CST 2009


Hi,

I have the following data structure:

col1 | col2 | col3

20080101|key1|4
20080201|key1|6
20080301|key1|5
20080301|key2|3.4
20080601|key2|5.6

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)]
    ???

Thanks in advance.


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