Find all local Maxima and Minima when x and y values are given as numpy arrays

Question

I have two arrays x and y as :

x = np.array([6, 3, 5, 2, 1, 4, 9, 7, 8])
y = np.array([2, 1, 3, 5, 3, 9, 8, 10, 7])

Answer 1

This will work fine.

Python uses += instead of ++.

Before you use i in a while loop you have to assign some value - in this case 0 - , this way initializing it to avoid error.

import numpy as np

x=np.array([6,3,5,2,1,4,9,7,8])
y=np.array([2,1,3,5,3,9,8,10,7])


sortId=np.argsort(x)
x=x[sortId]
y=y[sortId]
minm = np.array([])
maxm = np.array([])
i = 0
while i < y.size-1:
   while(y[i+1] >= y[i]):
      i+=1

   maxm=np.insert(maxm,0,i)
   i+=1
   while(y[i+1] <= y[i]):
      i+=1

   minm=np.insert(minm,0,i)
   i+=1

print minm, maxm