Using While Loop To Repeat A Step Of Loop To Reach The Proper Answer

I have the following code which I just write the final part of it. For some reasons we use random.normal values. As it is obvious the func function has three variables. My questio

Solution 1:

You can use a normal while loop and check the condition after calculating, for example:

for i in range (1,N):
    R=np.random.uniform(0,1)
    while True:
        Omn[i] = Omo[i-1] + 0.05 * np.random.normal()
        Wn[i] = Wo[i-1] + 0.05 * np.random.normal()
        Mn[i] = Mo[i-1] + 0.1 * np.random.normal()
        if Wo[i] <= 0and Omo[i] >= 0:
            break
    # rest of code

Solution 2:

Insert a while loop to repeat the calculations you require.

When L > R, Wo and Omo are updated with the Omn and Wn values. So if this values are Omn<0 or Wn>0 you need to re-calulate them. When L <= R, Wo and Omo are calculated from the previous iteration. Since the previous iteration already is Wo[i]<=0 and Omo[i]>=0 you don't need to repeat those calculations.

Thus, as shown in the code below, you only need to re-calculate the Omn and Wn variables:

Omo[0] = 0.24
Wo[0] = -0.2
Mo[0] = 1.0

N = 101for i inrange (1,N):
    is_valid = Falseif__debug__:
        print"Calculating position " + str(i)
    while (not is_valid):
        Omn[i] = Omo[i-1] + 0.05 * np.random.normal()
        Wn[i] = Wo[i-1] + 0.05 * np.random.normal()
        Mn[i] = Mo[i-1] + 0.1 * np.random.normal()

        if__debug__:
            print"- is_valid iteration values: " + str(Wn[i]) + " " + str(Omn[i])
            print"- is_valid previous values: " + str(Wo[i-1]) + " " + str(Omo[i-1])

        is_valid = Omn[i] >= 0and Wn[i] <= 0 

    R = np.random.uniform(0,1)
    L = exp(-0.5 * ( func(Omn[i], Wn[i], Mn[i] ) - func( Omo[i-1], Wo[i-1], Mo[i-1] )))

    if L > R:
        Omo[i] = Omn[i]
        Wo[i] = Wn[i]
        Mo[i] = Mn[i]
    else:
        Omo[i] = Omo[i-1]
        Wo[i] = Wo[i-1]
        Mo[i] = Mo[i-1]

    print(Wo[i], Mo[i], Omo[i])