title: How to add 2nd (circular) histogram reading from a csv file?
body: <p>I am new to python and have cobbled together some code that reads from the first index of .csv file (containing values in radians) and plots both a histogram and circular histogram. I would like to add a second (circular) histogram that reads from the 2nd index. Can anyone tell me how to do this?</p>
  
  <p><strong>Full code:</strong></p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  import csv
  
  with open('radians.csv', 'r') as f:
          reader=csv.reader(f)
          angles=[] # Initialise empty list
          next(reader) # Skip header line
          for row in reader:
                  angle = float(row[0]) 
                  angles.append(angle)
  
  bins_number = 18  # the [-180, 180) interval will be subdivided into this
  bins = np.linspace(-np.pi, np.pi, bins_number + 1)
  
  n, _, _ = plt.hist(angles, bins) # Create histogram
  plt.show()
  
  # Create circular histogram
  
  plt.clf()
  width = 2 * np.pi / bins_number
  ax = plt.subplot(1, 1, 1, projection='polar')
  bars = ax.bar(bins[:bins_number], n, width=width, bottom=10.0, align='edge', color='red')
  for bar in bars:
      bar.set_alpha(0.5)
  plt.show()
  </code></pre>
  
  <p><strong>Example rostral.csv values:</strong></p>
  
  <pre><code>1.214109733,2.678066227
  1.214109733,2.378408071
  1.214109733,2.378408071
  1.290159115,2.314906
  1.193219453,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  -1.7325846,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.208196994,2.314906
  1.248951138,2.314906
  0.945157766,2.314906
  -1.343997479,2.314906
  -1.561624822,2.314906
  -1.903895159,2.314906
  </code></pre>