Programmatically finding "significant" data points

[Fredrik Lundh]

"erikcw" wrote:

> I have a collection of ordered numerical data in a list.  The numbers
> when plotted on a line chart make a low-high-low-high-high-low (random)
> pattern.  I need an algorithm to extract the "significant" high and low
> points from this data.
>
> Here is some sample data:
> data = [0.10, 0.50, 0.60, 0.40, 0.39, 0.50, 1.00, 0.80, 0.60, 1.20,
> 1.10, 1.30, 1.40, 1.50, 1.05, 1.20, 0.90, 0.70, 0.80, 0.40, 0.45, 0.35,
> 0.10]

silly solution:

for i in range(1, len(data)-1):
    if data[i-1] < data[i] > data[i+1] or data[i-1] > data[i] < data[i+1]:
        print i

(the above doesn't handle the "edges", but that's easy to fix)

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