Printing output from a function wrapped with numba @jit

[abhishek...@gmail.com]

How can I print the variables PMean and PStd in the following code? I have been trying for nearly an hour with numba and my function mmm()! 

I have @jit outside my function, and return the variables PMean and PStd at the bottom of the code. But how can I get their values?

Here is my code: 

import numpy as np
import math
from numba import jit


Qpvec = np.logspace(-2,1,101,10)
lenQp = len(Qpvec)
delta = 1e-3
P0vec = Qpvec/delta
SimNum = 100
maxtime = 0.1
PTotStoch = np.zeros((SimNum,lenQp))
k_minus = 1e-3
k_cat = 1-1e-3
k_plus = 1e-3
zeta = 1e-4
D0 = 10000
kappa_M = (k_cat+k_minus)/zeta
QpDeg = np.true_divide(1000*D0*Qpvec*k_cat,1000*Qpvec + kappa_M)


@jit
def mmm():
    for lenQpInd in range(0,lenQp):
        for SimNumInd in range(0,SimNum):
            Qp = Qpvec[lenQpInd]
            P0 = P0vec[lenQpInd]
            DP0 = 0
            P = math.floor(P0)
            DP = DP0
            D = D0
            time = 0
   
            while time < maxtime:
                u_time = pl.rand()
                u_event = pl.rand()
                rates=np.array([Qp,zeta*P*D,k_minus*DP,k_cat*DP])
                PTot = P + DP
                kT = np.sum(rates)
                tot = np.cumsum(rates)
                deltaT = -np.log(1-u_time)/kT
                time += deltaT
                if time > maxtime:
                    PTotStoch[SimNumInd,lenQpInd] = PTot
                    break
                elif u_event*kT < tot[0]:
                    P += 1
                elif u_event*kT < tot[1]:
                    P -= 1
                    DP += 1
                    D -= 1
                elif u_event*kT < tot[2]:
                    P += 1
                    DP -= 1
                    D += 1
                elif u_event*kT < tot[3]:
                    DP -= 1
                    D += 1  
    PMean = PTotStoch.mean(axis=0)
    PStd = PTotStoch.std(axis=0)
    return PMean
    return PStd

Thank you.

[Joshua Adelman]

You need to return a tuple like:

return PMean, PStd

at the end of your mmm() method. Currently, the second `return` statement will not be executed. This is not specific to Numba and would be the case for any python function. Then you would call it like:

PMean, PStd = mmm()

and then you could access the variables outside of the function call. As far as printing goes, if you add:

from __future__ import print_function

to the top of your script, you can write `print(VariableName)` inside your function. Note that this changes the print semantics throughout your script to the Python3 syntax, so you'll want to read up on the difference.

Hope that helps,

Josh

[abhishek...@gmail.com]

So, I included the future statement to the top of my script, and then wrote 

    return PMean, PStd

    print(PMean)

    print(PStd)

at the bottom. It does not print anything still - I tried searching online for information on the future statement, but couldn't understand most of it. What am I missing?

[Joshua Adelman]

Once you execute the `return` line in a function, anything later is never reached. You will need to either print before the return or outside of the function after it is called. As far as the __future__ model goes, see the docs:

https://docs.python.org/2/library/__future__.html

Hope that helps,

Josh