def test_mann_whitney_u_R():
robjects = pytest.importorskip("rpi2.robjects")
random.seed(1)
a = list(range(30))
b = [x + 0.1 for x in a]
random.shuffle(a)
random.shuffle(b)
wilcox_test = robjects.r('wilcox.test')
for m in range(1, len(a) + 1):
for n in range(1, len(b) + 1):
u, p = statistics.mann_whitney_u(a[:m], b[:n])
r = wilcox_test(robjects.FloatVector(a[:m]),
robjects.FloatVector(b[:n]))
if max(m, n) <= 20:
err = 1e-10 # exact method
else:
# normal approximation
if min(m, n) < 3:
err = 0.4
elif min(m, n) < 10:
err = 0.1
else:
err = 0.05
assert u == r.rx('statistic')[0][0]
assert p == pytest.approx(r.rx('p.value')[0][0], abs=0, rel=err)
def test_mann_whitney_u_basic():
# wilcox.test(a, b, exact=TRUE)
a = [1, 2, 3, 4]
b = [0.9, 1.1, 0.7]
u, p = statistics.mann_whitney_u(a, b, method='exact')
assert u == 11
assert p == pytest.approx(0.11428571428571428, abs=0, rel=1e-10)
a = [1, 2]
b = [1.5]
u, p = statistics.mann_whitney_u(a, b, method='exact')
assert u == 1
assert p == 1.0
a = [1, 2]
b = [2.5]
u, p = statistics.mann_whitney_u(a, b, method='exact')
assert u == 0
assert p == pytest.approx(2 / 3, abs=0, rel=1e-10)
def check(x, y):
u0, p0 = stats.mannwhitneyu(x,
y,
alternative='two-sided',
use_continuity=False)
u, p = statistics.mann_whitney_u(x.tolist(),
y.tolist(),
method='normal')
assert u == u0
assert p == pytest.approx(p0, rel=1e-9, abs=0)
u, p = statistics.mann_whitney_u(x.tolist(),
y.tolist(),
method='exact')
assert u == u0
assert p == pytest.approx(p0, rel=5e-2, abs=5e-3)
u, p = statistics.mann_whitney_u(x.tolist(), y.tolist())
assert u == u0
assert p == pytest.approx(p0, rel=5e-2, abs=5e-3)
def test_mann_whitney_u_R():
random.seed(1)
a = list(range(10))
b = [x + 0.1 for x in a]
random.shuffle(a)
random.shuffle(b)
wilcox_test = robjects.r('wilcox.test')
for m in range(1, len(a) + 1):
for n in range(1, len(b) + 1):
u, p = statistics.mann_whitney_u(a[:m], b[:n])
r = wilcox_test(robjects.FloatVector(a[:m]),
robjects.FloatVector(b[:n]))
assert u == r.rx('statistic')[0][0]
assert p == pytest.approx(r.rx('p.value')[0][0], abs=0, rel=1e-10)