1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
import numpy as np
import pytest
import sympy
from numpy.testing import assert_equal
import brian2
from brian2 import (
DimensionMismatchError,
Expression,
Hz,
Statements,
get_dimensions,
ms,
mV,
second,
volt,
)
from brian2.core.preferences import prefs
from brian2.utils.logger import catch_logs
def sympy_equals(expr1, expr2):
"""
Test that whether two string expressions are equal using sympy, allowing
e.g. for ``sympy_equals("x * x", "x ** 2") == True``.
"""
s_expr1 = sympy.nsimplify(sympy.sympify(expr1).expand())
s_expr2 = sympy.nsimplify(sympy.sympify(expr2).expand())
return s_expr1 == s_expr2
@pytest.mark.codegen_independent
def test_expr_creation():
"""
Test creating expressions.
"""
expr = Expression("v > 5 * mV")
assert expr.code == "v > 5 * mV"
assert (
"v" in expr.identifiers
and "mV" in expr.identifiers
and not "V" in expr.identifiers
)
with pytest.raises(SyntaxError):
Expression("v 5 * mV")
@pytest.mark.codegen_independent
def test_split_stochastic():
tau = 5 * ms
expr = Expression("(-v + I) / tau")
# No stochastic part
assert expr.split_stochastic() == (expr, None)
# No non-stochastic part -- note that it should return 0 and not None
expr = Expression("sigma*xi/tau**.5")
non_stochastic, stochastic = expr.split_stochastic()
assert sympy_equals(non_stochastic.code, 0)
assert "xi" in stochastic
assert len(stochastic) == 1
assert sympy_equals(stochastic["xi"].code, "sigma/tau**.5")
expr = Expression("(-v + I) / tau + sigma*xi/tau**.5")
non_stochastic, stochastic = expr.split_stochastic()
assert "xi" in stochastic
assert len(stochastic) == 1
assert sympy_equals(non_stochastic.code, "(-v + I) / tau")
assert sympy_equals(stochastic["xi"].code, "sigma/tau**.5")
expr = Expression("(-v + I) / tau + sigma*xi_1/tau**.5 + xi_2*sigma2/sqrt(tau_2)")
non_stochastic, stochastic = expr.split_stochastic()
assert set(stochastic.keys()) == {"xi_1", "xi_2"}
assert sympy_equals(non_stochastic.code, "(-v + I) / tau")
assert sympy_equals(stochastic["xi_1"].code, "sigma/tau**.5")
assert sympy_equals(stochastic["xi_2"].code, "sigma2/tau_2**.5")
expr = Expression("-v / tau + 1 / xi")
with pytest.raises(ValueError):
expr.split_stochastic()
@pytest.mark.codegen_independent
def test_str_repr():
"""
Test the string representation of expressions and statements. Assumes that
__str__ returns the complete expression/statement string and __repr__ a
string of the form "Expression(...)" or "Statements(...)" that can be
evaluated.
"""
expr_string = "(v - I)/ tau"
expr = Expression(expr_string)
# use sympy to check for equivalence of expressions (terms may have be
# re-arranged by sympy)
assert sympy_equals(expr_string, str(expr))
assert sympy_equals(expr_string, eval(repr(expr)).code)
# Use exact string equivalence for statements
statement_string = "v += w"
statement = Statements(statement_string)
assert str(statement) == "v += w"
assert repr(statement) == "Statements('v += w')"
if __name__ == "__main__":
test_expr_creation()
test_split_stochastic()
test_str_repr()
|
