centre the peak at x=0 - numpy

Question

Right now the rectangle signal is centre on x = 4, how can I make it centre on x = 0
def rect(n,T):
a = np.zeros(int((n-T)/2,))
b = np.ones((T,))
c= np.zeros(int((n-T)/2,))
a1 = np.append(a,b)
a2 = np.append(a1,c)
return a2
x =rect(11,6)
plt.step(x, 'r')
plt.show()
This is so far that I wrote. Appreciate anyone can give the Idea

Answer 1

A method to center the rectangle at x=0 is to provide x values to plt.step. One way to accomplish this is to use numpy arange and center the x values around 0 by using the length of a2 returned in the rects function
# Changed to y because it will be our y values in plt.step
y = rect(11, 6)
# Add 0.5 so it's centered
x = np.arange(-len(y)/2 + 0.5, len(y)/2 + 0.5)
And then plot it using plt.step and setting where to mid (more info in the plt.step docs):
plt.step(x, y, where='mid', color='r')
Hope this helps. Here is the full code:
import numpy as np
import matplotlib.pyplot as plt
def rect(n, T):
a = np.zeros(int((n-T)/2,))
b = np.ones((T,))
c = np.zeros(int((n-T)/2,))
a1 = np.append(a, b)
a2 = np.append(a1, c)
return a2
y = rect(11, 6)
# Add 0.5 so it's centered
x = np.arange(-len(y)/2 + 0.5, len(y)/2 + 0.5)
plt.step(x, y, where='mid', color='r')
plt.show()