How to put a limit to my vector?

Question

I am doing a work, and in it I find a vector with possible values for a variable, however, the values that really meet the answer, are contained in the restriction 1.5 < R < 2 . How I would transform the vector R complete in the vector R real that meets the restriction? ie, the one that the house 0 begins with the value 1.5.

Ex: 1.5 < V < 2 , whereas V is a decreasing vector with 7 thousand houses.

Follow what I tried to do:

   
import numpy as np
import matplotlib.pyplot as plt

# Parametros Físicos:
m = 0.558 # massa (kg)

# Parâmetros Modais:
zeta = np.arange(0.000001,(np.sqrt(1/2)-0.001),0.0001) # fator amortecimento 

# Força externa aplicada:
F0 = 200 # amplitude da força (N)

rpico = np.sqrt(1-2*zeta**2)

ZY = (rpico**2)/((1-rpico**2)**2 + (2*zeta*rpico)**2)**(1/2)
i = j = 0
while i < 7061:
    i = i + 1
    if ZY[i]>1.5 and ZY[i]<2:
        zyl[j] = ZY[i]
        j = j+1 
        
        
plt.figure()
plt.plot(zeta,rpico)
plt.xlabel('Zeta')
plt.ylabel('rpico')
plt.title('-')
plt.grid (True)

plt.figure()
plt.plot(rpico,zyl)
plt.xlabel('rpico')
plt.ylabel('ZY')
plt.title('-')
plt.grid (True)

Answer 1

I made the following change to the code:

ZY = (rpico**2)/((1-rpico**2)**2 + (2*zeta*rpico)**2)**(1/2)
zyl = []

for item in ZY:
  if item > 1.5 and item < 2:
    zyl.append(item)

The idea is the same as yours: create a new array with valid values. However, in your code, you had not created the variable zyl before entering the loop, then there was an error. So I created it empty at the beginning.

Instead of traversing the ZY vector with two indices (i,j) it is easier to loop by iterating straight through the ZY values themselves.