Use dictionaries as requirements for if statements

Question

First of all, I`m sorry if I might ask this question and if it was already answered somewhere else. I couldnt find any solution for the following Problem:

I want to create a list where I apply multiple restricions. But instead of using over hundreads of if statements i just want to use a dictionary in one if statement to apply the requirements. So to say I want to use the keys of the dictionary as requirements and its values as factors for the data.

Lets take a look at a small example:

I want to create data for a countourplot where x/y range from [-50,50] in steps of 1 and the z function has requirements based on the if statements:

The following code is what works, but the more requirements I add the longer and more unreadalbe the code gets:

x = np.linspace(-50 , 50, 100)
y = np.linspace(-50 , 50, 100)
z = []
z_0 = 100
for i in x:
   for j in y:
      if i**2 + j**2 <= 10**2:
         z.append(1.9 * z_0)
      elif i**2 + j**2 <= 20**2:
         z.append(1.5 * z_0)
      elif i**2 + j**2 <= 30**2:
         z.append(1.4 * z_0)
      elif i**2 + j**2 <= 40**2:
         z.append(1.05 * z_0)
      else
         z.append(z_0)

This would create a map with radial decreasing hight as a function of z on different positions. Is it possible to do this in the following way which is way less redundant? My main problem is how to assing the correct value.

x = np.linspace(-50 , 50, 100)
y = np.linspace(-50 , 50, 100)
z = []
requirements_dict = {10:1,9, 20:1.5, 30:1.4, 40:1.05}
z_0 = 100
for i in x:
   for j in y:
      if i**2 + j**2 <= (each key of the requirements_dict) :
         z.append( (corresponding value of the requirements dict)   * z_0)
      else
         z.append(z_0)

Thanks in advance for the help and sorry again if this question was already asked.

Does this answer your question? [Check if all values in list are greater than a certain number](https://stackoverflow.com/questions/20229822/check-if-all-values-in-list-are-greater-than-a-certain-number) — RomanPerekhrest, Jan 16 '23 at 17:24

mr_mooo_cow · Accepted Answer · 2023-01-16T19:35:14.560

0

Is this what you're looking for?

EDIT:

import numpy as np

x = np.linspace(-50 , 50, 100)
y = np.linspace(-50 , 50, 100)
z = []
requirements_dict = {10: 1.9, 20: 1.5, 30: 1.4, 40: 1.05}
z_0 = 100
for i in x:
    for j in y:
        for key, value in requirements_dict.items():
            if i**2 + j**2 <= key:
                z.append(value * z_0)
                break
        else:
            z.append(z_0)

edited Jan 16 '23 at 19:35

answered Jan 16 '23 at 17:23

mr_mooo_cow

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Sorry but no this is something I already tried this myself. What your code creates is a list with 40.000 entires. The correct solution should have the size of len(x)*len(y) = 10.000. Your solution creates an entire z hight map for each requirement. I would need only one map that contains all requirements. But thanks for trying – Keeper Leucetius Jan 16 '23 at 18:02
I updated my answer. Can you let me know if that works for you. – mr_mooo_cow Jan 16 '23 at 19:35
Yes, now it is working fine. So it was just the break i was missing in my own try. Thank you very much :) – Keeper Leucetius Jan 18 '23 at 09:29
The break but also notice the else statement is on the for loop not the if statement and only executes when the break is not triggered. https://docs.python.org/3/tutorial/controlflow.html#break-and-continue-statements-and-else-clauses-on-loops – mr_mooo_cow Jan 18 '23 at 19:04

Use dictionaries as requirements for if statements

1 Answers1