For example I have two functions expressed with two lists:
x_1 = [0, 1, 2, 3, 4, 5]
y_1 = [2, 4, 1, 5, 1, 2]
x_2 = [2, 3, 4, 5, 6, 7]
y_2 = [2, 4, 1, 5, 1, 2]
and the result should be
x = [0, 1, 2, 3, 4, 5, 6, 7]
y = [2, 4, 3, 9, 2, 7, 1, 2]
Here I set the x values in the integer lattice but it is not necessary. But I guess one solution could be normalizing them onto the lattice and then add them.
Is there any simple method to do this? Numpy and Scipy are both available.
Thanks!
A simple illustration
Naive implementation:
x_1 = [0, 1, 2, 3, 4, 5]
y_1 = [2, 4, 1, 5, 1, 2]
x_2 = [2, 3, 4, 5, 6, 7]
y_2 = [2, 4, 1, 5, 1, 2]
f1 = dict(zip(x_1, y_1))
f2 = dict(zip(x_2, y_2))
x = list(set(f1.keys()) | set(f2.keys()))
y = [f1.get(k, 0) + f2.get(k, 0) for k in x]
print x
print y
Result:
[0, 1, 2, 3, 4, 5, 6, 7]
[2, 4, 3, 9, 2, 7, 1, 2]
numpy
has a 1d interpolation function, and scipy
has a more general one(s).
A simple approach with np.interp
:
x1,y1=[0,1,2,3,4,5],[2,4,1,5,1,2]
x2,y2=[2,3,4,5,6,7],[2,4,1,5,1,2]
x3 = np.arange(x1[0],x2[-1]+1) # or latice of your choice
np.interp(x3,x1,y1,0,0) + np.interp(x3,x2,y2,0,0)
producing:
array([ 2., 4., 3., 9., 2., 7., 1., 2.])
I told interp
to return 0 for values outside the x1
range, which seems to fit your addition scheme well.
A couple of other ways of constructing x3
:
Join the 2 lists, and ask for the unique values (sorted):
x3=np.unique(x1+x2)
or if the x
might already be arrays, concatenate them first:
x3=np.unique(np.concatenate([x1,x2]))
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