-
-
Notifications
You must be signed in to change notification settings - Fork 529
/
convert_to_casadi.py
222 lines (203 loc) · 9.31 KB
/
convert_to_casadi.py
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
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
#
# Convert a PyBaMM expression tree to a CasADi expression tree
#
from __future__ import annotations
import pybamm
import casadi
import numpy as np
from scipy import special
class CasadiConverter:
def __init__(self, casadi_symbols=None):
self._casadi_symbols = casadi_symbols or {}
pybamm.citations.register("Andersson2019")
def convert(
self,
symbol: pybamm.Symbol,
t: casadi.MX,
y: casadi.MX,
y_dot: casadi.MX,
inputs: dict | None,
) -> casadi.MX:
"""
This function recurses down the tree, converting the PyBaMM expression tree to
a CasADi expression tree
Parameters
----------
symbol : :class:`pybamm.Symbol`
The symbol to convert
t : :class:`casadi.MX`
A casadi symbol representing time
y : :class:`casadi.MX`
A casadi symbol representing state vectors
y_dot : :class:`casadi.MX`
A casadi symbol representing time derivatives of state vectors
inputs : dict
A dictionary of casadi symbols representing parameters
Returns
-------
:class:`casadi.MX`
The converted symbol
"""
try:
return self._casadi_symbols[symbol]
except KeyError:
# Change inputs to empty dictionary if it's None
inputs = inputs or {}
casadi_symbol = self._convert(symbol, t, y, y_dot, inputs)
self._casadi_symbols[symbol] = casadi_symbol
return casadi_symbol
def _convert(self, symbol, t, y, y_dot, inputs):
"""See :meth:`CasadiConverter.convert()`."""
if isinstance(
symbol,
(
pybamm.Scalar,
pybamm.Array,
pybamm.Time,
pybamm.InputParameter,
),
):
return casadi.MX(symbol.evaluate(t, y, y_dot, inputs))
elif isinstance(symbol, pybamm.StateVector):
if y is None:
raise ValueError("Must provide a 'y' for converting state vectors")
return casadi.vertcat(*[y[y_slice] for y_slice in symbol.y_slices])
elif isinstance(symbol, pybamm.StateVectorDot):
if y_dot is None:
raise ValueError("Must provide a 'y_dot' for converting state vectors")
return casadi.vertcat(*[y_dot[y_slice] for y_slice in symbol.y_slices])
elif isinstance(symbol, pybamm.BinaryOperator):
left, right = symbol.children
# process children
converted_left = self.convert(left, t, y, y_dot, inputs)
converted_right = self.convert(right, t, y, y_dot, inputs)
if isinstance(symbol, pybamm.Modulo):
return casadi.fmod(converted_left, converted_right)
if isinstance(symbol, pybamm.Minimum):
return casadi.fmin(converted_left, converted_right)
if isinstance(symbol, pybamm.Maximum):
return casadi.fmax(converted_left, converted_right)
# _binary_evaluate defined in derived classes for specific rules
return symbol._binary_evaluate(converted_left, converted_right)
elif isinstance(symbol, pybamm.UnaryOperator):
converted_child = self.convert(symbol.child, t, y, y_dot, inputs)
if isinstance(symbol, pybamm.AbsoluteValue):
return casadi.fabs(converted_child)
if isinstance(symbol, pybamm.Floor):
return casadi.floor(converted_child)
if isinstance(symbol, pybamm.Ceiling):
return casadi.ceil(converted_child)
return symbol._unary_evaluate(converted_child)
elif isinstance(symbol, pybamm.Function):
converted_children = [
self.convert(child, t, y, y_dot, inputs) for child in symbol.children
]
# Special functions
if symbol.function == np.min:
return casadi.mmin(*converted_children)
elif symbol.function == np.max:
return casadi.mmax(*converted_children)
elif symbol.function == np.abs:
return casadi.fabs(*converted_children)
elif symbol.function == np.sqrt:
return casadi.sqrt(*converted_children)
elif symbol.function == np.sin:
return casadi.sin(*converted_children)
elif symbol.function == np.arcsinh:
return casadi.arcsinh(*converted_children)
elif symbol.function == np.arccosh:
return casadi.arccosh(*converted_children)
elif symbol.function == np.tanh:
return casadi.tanh(*converted_children)
elif symbol.function == np.cosh:
return casadi.cosh(*converted_children)
elif symbol.function == np.sinh:
return casadi.sinh(*converted_children)
elif symbol.function == np.cos:
return casadi.cos(*converted_children)
elif symbol.function == np.exp:
return casadi.exp(*converted_children)
elif symbol.function == np.log:
return casadi.log(*converted_children)
elif symbol.function == np.sign:
return casadi.sign(*converted_children)
elif symbol.function == special.erf:
return casadi.erf(*converted_children)
elif isinstance(symbol, pybamm.Interpolant):
if symbol.interpolator == "linear":
solver = "linear"
elif symbol.interpolator == "cubic":
solver = "bspline"
elif symbol.interpolator == "pchip":
raise NotImplementedError(
"The interpolator 'pchip' is not supported by CasAdi. "
"Use 'linear' or 'cubic' instead. "
"Alternatively, set 'model.convert_to_format = 'python'' "
"and use a non-CasADi solver. "
)
else: # pragma: no cover
raise NotImplementedError(
f"Unknown interpolator: {symbol.interpolator}"
)
if len(converted_children) == 1:
return casadi.interpolant(
"LUT", solver, symbol.x, symbol.y.flatten()
)(*converted_children)
elif len(converted_children) in [2, 3]:
LUT = casadi.interpolant(
"LUT", solver, symbol.x, symbol.y.ravel(order="F")
)
res = LUT(casadi.hcat(converted_children).T).T
return res
else: # pragma: no cover
raise ValueError(
f"Invalid converted_children count: {len(converted_children)}"
)
elif symbol.function.__name__.startswith("elementwise_grad_of_"):
differentiating_child_idx = int(symbol.function.__name__[-1])
# Create dummy symbolic variables in order to differentiate using CasADi
dummy_vars = [
casadi.MX.sym("y_" + str(i)) for i in range(len(converted_children))
]
func_diff = casadi.gradient(
symbol.differentiated_function(*dummy_vars),
dummy_vars[differentiating_child_idx],
)
# Create function and evaluate it using the children
casadi_func_diff = casadi.Function("func_diff", dummy_vars, [func_diff])
return casadi_func_diff(*converted_children)
# Other functions
else:
return symbol._function_evaluate(converted_children)
elif isinstance(symbol, pybamm.Concatenation):
converted_children = [
self.convert(child, t, y, y_dot, inputs) for child in symbol.children
]
if isinstance(symbol, (pybamm.NumpyConcatenation, pybamm.SparseStack)):
return casadi.vertcat(*converted_children)
# DomainConcatenation specifies a particular ordering for the concatenation,
# which we must follow
elif isinstance(symbol, pybamm.DomainConcatenation):
slice_starts = []
all_child_vectors = []
for i in range(symbol.secondary_dimensions_npts):
child_vectors = []
for child_var, slices in zip(
converted_children, symbol._children_slices
):
for child_dom, child_slice in slices.items():
slice_starts.append(symbol._slices[child_dom][i].start)
child_vectors.append(
child_var[child_slice[i].start : child_slice[i].stop]
)
all_child_vectors.extend(
[v for _, v in sorted(zip(slice_starts, child_vectors))]
)
return casadi.vertcat(*all_child_vectors)
else:
raise TypeError(
f"""
Cannot convert symbol of type '{type(symbol)}' to CasADi. Symbols must all be
'linear algebra' at this stage.
"""
)