title: how to stop pyplot from reversing the values in my x-axis
body: <p>Signal is 2048 long integer array. The plot is shown below.</p>
  
  <p><a href="https://i.stack.imgur.com/svdk9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/svdk9.png" alt="enter image description here"></a></p>
  
  <p>See that the velocity axis has negative values on left and positive values on the right. When I created the velocity array it starts with positive numbers and ends with negative numbers, why does the x axis reverse the plot? how do I get it to plot left to right instead of right to left? (positive to negative instead of negative to positive)</p>
  
  <p>thanks</p>
  
  <hr>
  
  <pre><code>import numpy.polynomial.polynomial as poly
  from scipy import asarray as ar,exp, optimize
  import numpy as np
  import matplotlib.pyplot as plt
  from scipy.optimize import curve_fit
  
  signal = np.genfromtxt("rawdata/g924310/r_g924310_b1.txt")
  
  for i in range(1,2048,1):
      vel[i] = (1024.5 - i)* 0.137177
  signal = np.genfromtxt("rawdata/g924310/r_g924310_b1.txt")
  
  plt.plot(vel,signal,'b+:',label='scan')
  plt.legend()
  plt.title('1667 MHz (92.4, -31.0) - Antenna Temp v Vel')
  plt.xlabel('Velocity')
  plt.ylabel('Antenna Temp (K)')
  plt.show()
  </code></pre>