Question:
I have a list of arrays such as:
a = [array([0, 4]), array([1, 3, 2])]
From another variable X, I want to take two subsets which are chosen by the index in each array in a.
X = [0.1, 0.7, 0.9, 0.2, 0.3]
What I want to have is now:
result_1 = [0.1, 0.3]
result_2 = [0.7, 0.2, 0.9]
My solution would be to use a for loop such as:
def getresult(X, indices):
result = []
for i in indices:
result.append(X[i])
retu result
This works fine:
getresult(X, a[0])
[0.1, 0.3]
My previous experience with programming suggest, that there is a much more beautiful and simple way to do so and that this is the place to ask.
Background/application:
Background: Crossvalidation for parameter optimization.
I have a list containing datapoints such as
X = [0.1, 0.7, 0.9, 0.2, 0.3]
Now I want to repeatedly take z samples out of that list (which actually is much bigger than this example). Therefore I create a new variable:
indices = np.arange(0,len(X),1)
HERE: [0, 1, 2, 3, 4]
Which then i shuffle and create nfold samples:
np.random.shuffle(indices)
nfold_indices = np.array_split(indices,nfolds)
HERE with nfolds = 2: nfold_indices = [array([0, 4]), array([1, 3, 2])]