将输出循环到列表或numpy数组，以及一个NoneTypeError

Question

Here's my code:

# Libs
import numpy as np

# Isostatic model:

def airy(t,tref=35.,rhoM=3.2,rhoC=2.7,mode=None,rate=None,hlimit=None):
  # Equilibrium ratios:
  er = rhoC / (rhoM-rhoC)
  di = rhoC/rhoM
  # Static buoyancy equation:
  excess = t-tref
  hi = excess * (1-di)
  ri = excess - hi  
  # Mode results:
  if mode == 'Initial':
    print("Model parameters: Crustal density =",rhoC,"Mantle density =",rhoM)
    print("Mountain height (Km) =",np.round(hi, 3))
    print("Root thickness (Km) =",np.round(ri, 3))
    print("Ratio of height to root =",er)
    return ri, hi
  elif mode=='Erosive':
    # Initialise loop
    counter = 0
    ht = hi
    while ht >= hlimit:
      counter = counter+1
      excess = t-tref
      ht = excess * (1-di)
      rt = excess - ht
      ht = ht*np.exp(rate*counter)
      t = ht+rt+tref
      print(rt, ht, counter)
  elif mode==None:
    return ri, hi

tref = 35.  
it = tref*1.5
print("Initial thickness =",it)
ir, ih = airy(it, mode='Initial')
rt, ht, tstep = airy(it, mode='Erosive', rate=-0.025,hlimit=0.5)

It's taken me bl*ody ages to get even to this stage with the loop and its still not what I'm after!

I would like to get a list or array of values for each iteration of the loop for the variables rt and ht. At the moment this works and prints the correct values for the loop, but also results in a NoneTypeError. If I add a return rt, ht, counter then the result is a single value, not a list/array.

So I've seen this answer, but ideally want this inside one function and I can't see where I'm supposed to use a list in the loop.

Any help would be appreciated! Thanks

Answer 1

You forgot to return the three-valued tuple:

def airy(t,tref=35.,rhoM=3.2,rhoC=2.7,mode=None,rate=None,hlimit=None):
  # Equilibrium ratios:
  er = rhoC / (rhoM-rhoC)
  di = rhoC/rhoM
  # Static buoyancy equation:
  excess = t-tref
  hi = excess * (1-di)
  ri = excess - hi  
  # Mode results:
  if mode == 'Initial':
    print("Model parameters: Crustal density =",rhoC,"Mantle density =",rhoM)
    print("Mountain height (Km) =",np.round(hi, 3))
    print("Root thickness (Km) =",np.round(ri, 3))
    print("Ratio of height to root =",er)
    return ri, hi
  elif mode=='Erosive':
    # Initialise loop
    counter = 0
    ht = hi
    l_ht = []
    l_rt_ = []
    l_counter = []
    while ht >= hlimit:
      counter = counter+1
      excess = t-tref
      ht = excess * (1-di)
      rt = excess - ht
      ht = ht*np.exp(rate*counter)
      t = ht+rt+tref
      print(rt, ht, counter)
      l_rt.append(rt)
      l_ht.append(ht)
      l_counter .append(counter)
    return l_rt, l_ht, l_counter # HERE
  elif mode==None:
    return ri, hi

Would return None otherwise, and fail with the unpacking.

Answer 2

    elif mode=='Erosive':
        # Initialise loop
        counter = 0
        ht = hi
        while ht >= hlimit:
          counter = counter+1
          excess = t-tref
          ht = excess * (1-di)
          rt = excess - ht
          ht = ht*np.exp(rate*counter)
          t = ht+rt+tref
          print(rt, ht, counter)
#-------> where is a return statement?