永久更改 python 中 for 循环内的参数公式

Question

I want to run a nested for loop in python, where it should run until a specific threshold of a variable, defined in the loop. After the threshold, I would like to continue the loop and change the formula of the parameter permanently. I hope with the following example, that I will be able to show you what I want to do.

import numpy as np
a=np.linspace(1,10,10)
b=np.linspace(0,20,10)

t=np.zeros([len(a),len(b)])

for i in range(0,len(a)):
    for j in range(0,len(b)):
        t[i,j]=a[i]+3*b[j]
        if t[i,j]>30:
           t[i,j]=a[i]+b[j]
        else:
           continue      

In the specific loop the equation of t changes when the threshold value is reached and afterwards it goes back to the initial and continues in the loop. My aim is after the threshold value, to change permanently the equation of t and continue with that for the rest of the loop.

Answer 1

You might like to use an additional variable to indicate if you have reached your desired criterion to switch to a different function:

Example:

import numpy as np
a=np.linspace(1,10,10)
b=np.linspace(0,20,10)

t=np.zeros([len(a),len(b)])

threshold_flag = False
for i in range(0,len(a)):
    for j in range(0,len(b)):
        if threshold_flag:
            t[i,j] = a[i] + b[j]
        else:
            t[i,j]=a[i]+3*b[j]
            if t[i,j]>30:
               t[i,j] = a[i] + b[j]
               threshold_flag = True
            else:
               continue

Answer 2

Do you mean something like this?

import numpy as np
a=np.linspace(1,10,10)
b=np.linspace(0,20,10)

t=np.zeros([len(a),len(b)])

THRESHOLD = 30
reached_threshold = False

for i in range(0,len(a)):
    for j in range(0,len(b)):
        if not reached_threshold:
            t[i,j]=a[i]+3*b[j]
            if t[i,j] > THRESHOLD:
                reached_threshold = True
                t[i,j]=a[i]+b[j] 
        else:
            t[i,j]=a[i]+b[j]