Unexpected behavior of canonical correlation analysis (CCA)

Description

Given two view matrices X and Y, CCA should return the n_components linear combinations of the elements in X's and Y's vectors with the largest correlation, i.e the first component has the largest correlation, the second one has the second-largest correlation in a direction that is uncorrelated with the first one, etc. However, in the following code, the second columns are clearly less correlated than the third columns:

Steps/Code to Reproduce

from sklearn.cross_decomposition import CCA
import numpy as np
from scipy import stats

X = [[0.006061109337620652, 0.0392466675239141, -0.04312459861840733], [-0.6652995467596429, 0.2076410843346226, -0.7817536882379651], [-1.4060868112838942, -0.055029478343267685, -1.006415484608637], [-2.170613455952169, -0.15770102997315535, -1.5223958036356375], [-2.895702070412092, -0.20498481413822175, -1.8232022285963847], [-3.687452614812402, -0.543003880524402, -2.2952030829468533], [-4.206168972149556, -0.3365693935548624, -2.841946351795423], [-5.231288268781064, -0.8024321344988571, -3.40532581256557], [-6.095805742721522, -0.9381144689340173, -3.593752186094848], [-6.297988264542059, -0.7231985020991631, -3.9435579269998406], [-7.10897027952524, -0.8639925998765747, -4.264992629284153], [-8.116238092376772, -1.0123970020855437, -4.96858178622968], [-8.969468878952105, -1.0235782019578692, -5.617282941713933], [-9.839359511108077, -1.2819621078971968, -5.8901943190245625], [-10.181936322525571, -0.9904671991812529, -6.240811384647836]]
Y = [[0.032927114749911154, 0.21320841666565743, -0.23427536580450153], [1.431742605643286, 0.23963850202268067, 0.8438745303679628], [2.908798834568648, 0.7357229001312737, 1.325345683629048], [4.438824821921929, 0.9473643810538429, 2.35038560647864], [5.887201894166226, 1.0302756424934638, 2.964806513433767], [7.409049064480012, 1.3070946380395154, 4.347473875547982], [8.51501831350366, 1.3380108570442941, 4.9533251686263275], [10.57244384646805, 2.31627294094068, 6.028949244604159], [12.22872203222364, 2.1165257564864675, 6.923464021607424], [12.664660419747504, 1.8911363532121173, 7.398432173930664], [14.29235367239137, 2.2098221962551343, 8.000538342827351], [16.327977920399373, 2.643183255720207, 9.257671785118596], [18.081288169620517, 2.968898443090926, 10.221747267811098], [19.754046559146662, 3.051682253577557, 11.244435627784393], [20.466418131910004, 2.644933083198568, 11.752014917896375]]

cca = CCA(n_components=3)
cca.fit(X, Y)
X_transformed, Y_transformed = cca.transform(X, Y)

print(X_transformed)

[[ 1.64277244  0.08237031  0.11724683]
 [ 1.41457457 -0.11600721  0.07162219]
 [ 1.18686358  0.00666119  0.08822118]
 [ 0.94070119 -0.02504267 -0.0112954 ]
 [ 0.71314666  0.02919558  0.25990473]
 [ 0.46246267  0.05607036 -0.16424275]
 [ 0.28625435 -0.09546609 -0.02850206]
 [-0.03644528 -0.03407977 -0.55790786]
 [-0.30127324  0.12266269 -0.12622283]
 [-0.37581414 -0.01941656 -0.0343278 ]
 [-0.62900674  0.05973748  0.13448604]
 [-0.95400947  0.0082079  -0.05487306]
 [-1.23214839 -0.07548718 -0.08864002]
 [-1.50031366  0.05776429  0.00665019]
 [-1.61776455 -0.0571703   0.38788062]]

print(Y_transformed)

[[ 1.64131294  0.01428169  0.11343087]
 [ 1.41330957 -0.06169376  0.06929115]
 [ 1.18580457  0.04946041  0.0853499 ]
 [ 0.9398609   0.01613582 -0.01092778]
 [ 0.71251056  0.06356946  0.25144578]
 [ 0.46205587 -0.05371303 -0.15889725]
 [ 0.28599564 -0.05298207 -0.02757442]
 [-0.03641563  0.02220818 -0.53975   ]
 [-0.30099795  0.01004611 -0.12211474]
 [-0.37547807 -0.063071   -0.03321056]
 [-0.62844374  0.02679924  0.13010901]
 [-0.95315959  0.0185694  -0.05308714]
 [-1.23105629  0.03726576 -0.08575511]
 [-1.49897395  0.01483407  0.00643375]
 [-1.61632484 -0.04171028  0.37525653]]

Expected Results

The correlation between the third columns of X_transfomed and Y_transformed is approximately 1, while the correlation between the second columns is only 0.389. Therefore, I expected the third column to appear in the place of the second column.

Actual Results

When I run CCA with n_components=2 I get the first and second columns, while I should have gotten the first and the third.

Versions

Linux-4.13.0-16-generic-x86_64-with-Ubuntu-17.10-artful
Python 3.6.3 (default, Oct 3 2017, 21:45:48)
NumPy 1.14.3
SciPy 1.2.0
Scikit-Learn 0.19.1

Start at the sklearn.cross_decomposition.CCA entry point and rerun the supplied X/Y reproduction with n_components set to 2 and 3. Compare the correlations of the transformed columns against the stated expected ordering, then inspect the relevant CCA implementation and existing tests. Done means the behavior is clarified or corrected and covered by a regression test.