How to pass arguments as tuple to odeint?

Question

I wanted to use odeint of scipy with a function

def func(y,t,a=123,b=456)

then use it as

odeint(func,y0,t)

If I want to change the values a and b using args

odeint(func,y0,t,args=(a=1,b=2))

It complains that arguments are not tuple.
It may be a very elementary question,
how can I pass keyword arguments as a tuple?

odeint(func,y0,t,args=...?)

Asked By: user2775514

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Source

Answer 1

You just need to remove the assignments to make a legit tuple:

odeint(func,y0,t,args=(123, 456))

There’s another answer here with an example of calling odeint with arguments.

Answered By: pneumatics

Answer 2

I know this is old, but here is my solution:

first, we must segment the time we are going to use according to the parameters we are going to use.

then, we made a zip(time, a, b) loop, therefore, a and b must have the same length.

def time_segment(tobesimilar, dt_float=0.01):
    '''time_segment produces an array of dt-length time intervals, the shape of the output is ( len(tobesimilar), 2)
    inputs: 
        tobesimilar: array or list, which length (len) is only used as a reference     to be duplicated 
        dt: float, dt refers to what is going to be our integration step, in this case, it is used as the interval length.
    output: 
        tmp: array, such as tmp.shape= (len(tobesimilar),2) 
        '''
    newt=np.arange(0,len(tobesimilar)*dt, dt)

    #segments the nwet[a,b] in n intervals [a_i,b_i]
    #whith a_0 = 0 and b_n = newt[-1] 
     if len(newt)%2==0: #if len(newt) is even, no problem
         tmp = [[newt[i],newt[i+1]] for i in range(len(newt)-1)]
     else: #if len(newt) is odd, just add an item
         newt= np.append(newt,newt[-1]+dt)
         tmp = [[newt[i],newt[i+1]] for i in range(len(newt)-1)]

     #turns tmp into an array cause <3 (heart) numpy
     tmp=np.array(tmp)

     return tmp

def func(t,y,a=123,b=456):
   return print( "what ever your function does" )

a=np.array([1,2,3,45,67,88])
b=np.array([54,4,1,99,42,100])
y_0= 0 #initial condition
solution=np.asanyarray([y_0]) #preallocate the output
time=time_segment(vol, dt=dt)

for ts in zip(time, a, b):
    y = odeint(func, y0=solution[-1], t=ts[0], args=(ts[1],ts[2],), tfirst= True)
    solution = np.append(solution, [y.T[0][1]])

Answered By: Erre Hache

How to pass arguments as tuple to odeint?

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