Question

I am getting the following error when running my code:

Typeerror: lambda() takes exactly 4 arguments (3 given)

Here is my code – my error is coming from the last line of code (I think) where I am trying to implement Scipy’s optimization algorithm fmin

from pylab import * 
import pylab as pl
from numpy import *
from scipy.optimize import fmin
from scipy import integrate
import numpy as np

def ode(s,t,k1,k2):
    A = s[0]
    B = s[1]
    C = s[2]
    dA = -k1*A
    dB = k1*A-k2*B
    dC = k2*B
    ds = [dA,dB,dC]
    return ds

def myllsq(teta,s0,t,s):
    y_obs = s
    k1 = teta[0]
    k2 = teta[1]
    s = integrate.odeint(ode,s0,t,args=(k1,k2))
    y_cal = s[:,1]
    lsq = sum(y_obs-y_cal)**2
    return lsq 

e = lambda teta,s0,t,s: myllsq(teta,s0,t,s)

if __name__ == '__main__': 
    n = 10
    tmin = 0.0
    tmax = 9
    k1 = 0.3
    k2 = 0.2
    s0 = [1,0,0]
    t = linspace(tmin,tmax,n)
    s = [0.000,0.416,0.489,0.595,0.506,0.493,0.458,0.394,0.335,0.309]
    teta = [k1,k2]
    print e(teta,s0,t,s)
    fmin(e,teta,args=(t,s),maxiter=10000,maxfun=10000)

Answer 1

I think it should be something like:

fmin(e,teta,args=(s0,t,s),maxiter=10000,maxfun=10000)

instead of:

fmin(e,teta,args=(t,s),maxiter=10000,maxfun=10000)

You’re not passing the s0 list to your function.

As a side note, there’s no real need for lambda here. You could just pass myllsq directly — e is just a less efficient version of myllsq.