Hi Michael,
Try this:
import openturns as ot
Q = 1013.Ks = 30.Zv = 50.Zm = 55.Hd = 8Zb = 55.5L = 5000B = 300X =
[Q,Ks,Zv,Zm,Hd,Zb,L,B]
inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B'] formula = 'var alpha :=
(Zm - Zv)/L; H := (Q/(Ks*B*sqrt(alpha)))^(3.0/5.0); var Zc := H + Zv; var Zd :=
Zb + Hd; S := Zc - Zd'outputs = ['H', 'S']myFunction =
ot.SymbolicFunction(inputs, outputs, formula)print(myFunction(X))
In the case of multiple outputs defined using a unique formula, you have to:1)
provide the formula as a single string2) declare the intermediate results you
want to reuse but not to output using the 'var' qualifier3) provide the list of
outputs as a sequence of strings
Cheers
Régis
Le vendredi 3 août 2018 à 18:10:15 UTC+2, BAUDIN Michael
<[email protected]> a écrit :
Hi,
I tried the feature you showed with the following script :
Q = 1013.
Ks = 30.
Zv = 50.
Zm = 55.
Hd = 8
Zb = 55.5
L = 5000
B = 300
X = [Q,Ks,Zv,Zm,Hd,Zb,L,B]
inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B']
formula = ['var alpha := (Zm - Zv)/L; H := (Q/(Ks*B*sqrt(alpha)))^(3.0/5.0);
var Zc := H + Zv; var Zd := Zb + Hd; S := Zc - Zd']
outputs = ['H', 'S']
myFunction = ot.SymbolicFunction(inputs, outputs, formula)
print(myFunction(X))
But the following exception is generated :
NotImplementedError: Wrong number or type of arguments for overloaded function
'new_SymbolicFunction'.
Possible C/C++ prototypes are:
OT::SymbolicFunction::SymbolicFunction()
OT::SymbolicFunction::SymbolicFunction(OT::String const &,OT::String const
&)
OT::SymbolicFunction::SymbolicFunction(OT::Description const
&,OT::Description const &)
OT::SymbolicFunction::SymbolicFunction(OT::Description const
&,OT::Description const &,OT::String const &)
OT::SymbolicFunction::SymbolicFunction(OT::SymbolicFunction const &)
I also tried a simpler version :
inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B']
formula = ['alpha := (Zm - Zv)/L; H := (Q/(Ks*B*sqrt(alpha)))^(3.0/5.0); Zc :=
H + Zv; Zd := Zb + Hd; S := Zc - Zd']
myFunction = ot.SymbolicFunction(inputs, formula)
print(myFunction(X))
TypeError: InvalidArgumentException : Errors found when parsing expression
'alpha := (Zm - Zv)/L; H := (Q/(Ks*B*sqrt(alpha)))^(3.0/5.0); Zc := H + Zv; Zd
:= Zb + Hd; S := Zc - Zd': ERR189 - Undefined symbol: 'alpha'
What is the trick you used to make it work ?
(This is with OT 1.11).
Best regards,
Michaël
Michaël BAUDIN
Ingénieur - Chercheur
EDF – R&D
Département Management des Risques Industriels
6, quai Watier
78401 CHATOU
[email protected]
Tél. : 01 30 87 81 82
Fax : 01 30 87 82 13
-----Message d'origine-----
De : [email protected] [mailto:[email protected]]
Envoyé : lundi 12 mars 2018 21:26
À : BAUDIN Michael <[email protected]>
Cc : [email protected]
Objet : Re: [ot-users] Simplified symbolic functions
Hello Michael,
We investigated using ExprTk to parse analytical formulas instead of muParser,
it is known to be faster.
Almost all muParser formulas can be parsed by ExprTk without changes, but it
also provides many more features. And multiple outputs are trivial with this
backend.
This has been implemented on current master, your example can be written:
inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B'] outputs = ['H', 'S']
formula = """var alpha := (Zm - Zv)/L; H := (Q/(Ks*B*sqrt(alpha)))^(3.0/5.0);
var Zc := H + Zv; var Zd := Zb + Hd; S := Zc - Zd;"""
myFunction = SymbolicFunction(inputs, outputs, formula)
This is almost straightforward; input and output variables are declared, all
other variables must be prefixed by the keyword 'var', assignment is ':=', and
statements must be separated by semicolons.
But Python can be as fast as SymbolicFunction; pull request #699 avoids copies
between OT and Python, your code could be rewritten as
import numpy as np
def functionCrueSample(X) :
Q, Ks, Zv, Zm, Hd, Zb, L, B = np.array(X, copy=False).T
alpha = (Zm - Zv)/L
H = (Q/(Ks*B*np.sqrt(alpha)))**(3.0/5.0)
Zc = H + Zv
Zd = Zb + Hd
S = Zc - Zd;
Y = np.zeros((len(H), 2))
Y[:,0] = H
Y[:,1] = S
return Y
myFunction = PythonFunction(8, 2, func_sample=functionCrueSample)
Denis
2018-02-14 12:30 GMT+01:00 BAUDIN Michael <[email protected]>:
> Hi,
>
>
>
> I have a symbolic function that I would like to simplify and I do not
> see how.
>
>
>
> Here is the test case. The function has 8 inputs and 2 outputs. In
> Python it is simple to define :
>
>
>
> def functionCrue(X) :
>
> Q, Ks, Zv, Zm, Hd, Zb, L, B = X
>
> alpha = (Zm - Zv)/L
>
> H = (Q/(Ks*B*sqrt(alpha)))**(3.0/5.0)
>
> Zc = H + Zv
>
> Zd = Zb + Hd
>
> S = Zc - Zd
>
> return [H,S]
>
> myFunction = PythonFunction(8, 2, functionCrue)
>
>
>
> As you can see, the code is simplified by intermediate variables which
> are used by subsequent Python statements. For exemple, the slope of
> the river alpha is first computed, then the height H is computed
> depending on the slope. Then the variable S is computed based on Zc
> and Zd, where Zc is computed depending on the height H.
>
>
>
> When I define the function as a symbolic function, the current
> definition is more involved.
>
>
>
> inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B']
>
> formulas = ['(Q/(Ks*B*sqrt((Zm -
> Zv)/L)))^(3.0/5.0)','(Q/(Ks*B*sqrt((Zm - Zv)/L)))^(3.0/5.0)+Zv-(Zb +
> Hd)']
>
> myFunction = SymbolicFunction(inputs, formulas)
>
>
>
> As you can see, I cannot reuse the value of the first output into the
> second output.
>
>
>
> The following interface would be much easier to use. The formulas
> variable is a list of couples, where the first item is the name of the
> output variable and the second item is the string to evaluate it.
>
>
>
> inputs = ['Q', 'Ks', 'Zv', 'Zm', 'Hd', 'Zb', 'L', 'B']
>
> output1 = [‘alpha’, '(Zm - Zv)/L']
>
> output2 = [‘H’, '(Q/(Ks*B*sqrt(alpha)))^(3.0/5.0)']
>
> output3 = [‘Zc’, 'H + Zv']
>
> output4 = [‘Zd’, 'Zb + Hd']
>
> output5 = [‘S’, 'Zc - Zd']
>
> formulas = [output1,output2,output3,output4,output5]
>
> myFunction = SymbolicFunction(inputs, formulas)
>
>
>
> Is there another way of doing this ? Do you agree that the suggestion
> is worth being developed ?
>
>
>
> Best regards,
>
>
>
> Michaël
>
>
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Ce message et toutes les pièces jointes (ci-après le 'Message') sont établis à
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destination, toute diffusion ou toute publication totale ou partielle, est
interdite sauf autorisation expresse.
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copier, de le faire suivre, de le divulguer ou d'en utiliser tout ou partie. Si
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ainsi que toutes ses copies, et de n'en garder aucune trace sur quelque support
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l'expéditeur par retour du message.
Il est impossible de garantir que les communications par messagerie
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erreur ou virus.
____________________________________________________
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addressees. The information contained in this Message is confidential. Any use
of information contained in this Message not in accord with its purpose, any
dissemination or disclosure, either whole or partial, is prohibited except
formal approval.
If you are not the addressee, you may not copy, forward, disclose or use any
part of it. If you have received this message in error, please delete it and
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