Extracting certain range of values from an array

Question

I am trying to extract the data from 15020 to -15431. Is it possible for me to extract such a range? The x value is often different as it is read by a file.

Range
x = 15021,14999,14888,...,0,-1000,-14000,-15431,-14000,-2000,0,1000,7000,15890
  # from here to---------------------------here

Here, 15021 is the first value.

-15431 is the minimum value. minimum(x) = -15431

How can I extract data from the first value to the min value?

Depends. If the array never changes, then you can use [array slicing](http://stackoverflow.com/questions/509211/pythons-slice-notation) with hardcoded indexes, otherwise you'll need to search the array. — Chris Laplante, Nov 04 '13 at 01:25
What are you *really* trying to do? Are you, perhaps, trying to find the longest initial sequence that's strictly decreasing? — Tim Peters, Nov 04 '13 at 01:31
Is that meant to represent the contents of your file or is it meant to be code? — YXD, Nov 04 '13 at 01:32
I am trying to plot a interpolation graph but for interp1d it only take from postive to 0 to negative anything else is a no. thus i have to know how to extract out positive to negative value @TimPeters — , Nov 04 '13 at 01:33
@ZhenHui, but the example you gave includes 3 negative values, not 1. And then it does *not* include two more negative values following -15431. It's very unclear why you stopped at -15431. Why didn't you stop at -1000? At -14000? At -2000? What's special about -15431? — Tim Peters, Nov 04 '13 at 01:35
Sorry i might not explained clearly.. As -15431 is like the lowest range for negative value. maybe i can get min(x) to obtain the negative value @TimPeters — , Nov 04 '13 at 01:37
Then read my first question again ;-) It sure sounds like *are* you trying to find the longest initial sequence that's strictly decreasing (or maybe just non-increasing). Your main problem here is that you really haven't defined what you need :-) — Tim Peters, Nov 04 '13 at 01:39

score 3 · Accepted Answer · answered Nov 04 '13 at 01:42

Assuming x is a list, the slice from the first value to the smallest value can be written

x[:x.index(min(x)) + 1]

Like so:

>>> x = [15021,14999,14888,0,-1000,-14000,-15431,-14000,-2000,0,1000,7000,15890]
>>> x[:x.index(min(x)) + 1]
[15021, 14999, 14888, 0, -1000, -14000, -15431]

Extracting certain range of values from an array

1 Answers1