title: Python scatter plot and matplotlib
body: <p>I have a scatter plot in python onto which i want to draw a trendline. From the various examples i have found around the internet to learn how to draw the trendline my code is the following:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  import numpy as np
  
  x=np.array([9.80,13.20,13.46,14.09,13.96,10.77,8.79,8.61,8.83,11.08,10.13,12.40,9.90,10.96,12.75,11.79,11.79,12.38,12.78,13.08,12.83,12.57,12.96,12.90,12.91,13.67,12.83,12.50,12.42,12.83,12.82,12.70,12.60,12.90,13.20])
  y=np.array([0.0706,0.0969,0.0997,0.1031,0.0848,0.1044,0.0815,0.1030,0.0783,0.0970,0.1193,0.0796,0.0697,0.0738,0.0895,0.0912,0.0887,0.0973,0.0942,0.1052,0.0984,0.0965,0.0903,0.0876,0.1071,0.0872,0.0857,0.0967,0.0926,0.0837,0.0967,0.0935,0.0946,0.0930,0.0758
  ])
  
  plt.scatter(x, y)
  fit = np.polyfit(x, y, deg=4)
  p = np.poly1d(fit)
  plt.plot(x,p(x),"r--")
  plt.show()
  </code></pre>
  
  <p>But the result line instead of being a curve line is just a mix of lines. Can anyone please explain my mistake?</p>