title: how to plot graded letters like A* in matplotlib
body: <p>i'm a complete beginner and i have a college stats project, im comparing <strong>exam scores</strong> for our year group and the one below. i collected my own data and since i do cs i decided to try visualize the data with pandas and matplotlib (my first time). i was able to read the csv file into a dataframe with columns = Level,Grade,Difficulty,Happy,MAG. <strong>Level</strong> is just ' year group ' e.g. AS or A2. and <strong>MAG</strong> is like a minimum expected grade, the rest are numeric values out of 5.</p>
  <p>i want to do some type of plotting but i cant' seem to get it work.
  <strong>i want to plot</strong> revision against difficulty? <strong>for AS group</strong> and try show a correlation. i also want to show a barchart ( if appropriate ) for Grade Vs MAG.</p>
  <p>here is the csv <a href="https://docs.google.com/spreadsheets/d/169UKfcet1qh8ld-eI7B4U14HIl7pvgZfQLE45NrleX8/edit?usp=sharing" rel="nofollow noreferrer">https://docs.google.com/spreadsheets/d/169UKfcet1qh8ld-eI7B4U14HIl7pvgZfQLE45NrleX8/edit?usp=sharing</a></p>
  <p>this is the code so far:</p>
  <pre><code>import pandas as pd
  import matplotlib.pyplot as plt
  import numpy as np
  df = pd.read_csv('Report Task.csv')
  df.columns = ['Level','Grade','Difficulty','Revision','Happy','MAG'] #numerical values are out of 5
  df[df.Level.str.match('AS')] #to get only AS group
  plt.plot(df.Revision, df.Difficulty)
  </code></pre>
  <p>this is my first time ever posting on stack so im really sorry if i did something wrong.</p>