# Setting the positions and width for the bars
pos = list(range(len(df['pre_score'])))
width = 0.25
# Plotting the bars
fig, ax = plt.subplots(figsize=(10,5))
# Create a bar with pre_score data,
# in position pos,
plt.bar(pos,
#using df['pre_score'] data,
df['pre_score'],
# of width
width,
# with alpha 0.5
alpha=0.5,
# with color
color='#EE3224',
# with label the first value in first_name
label=df['first_name'][0])
# Create a bar with mid_score data,
# in position pos + some width buffer,
plt.bar([p + width for p in pos],
#using df['mid_score'] data,
df['mid_score'],
# of width
width,
# with alpha 0.5
alpha=0.5,
# with color
color='#F78F1E',
# with label the second value in first_name
label=df['first_name'][1])
# Create a bar with post_score data,
# in position pos + some width buffer,
plt.bar([p + width*2 for p in pos],
#using df['post_score'] data,
df['post_score'],
# of width
width,
# with alpha 0.5
alpha=0.5,
# with color
color='#FFC222',
# with label the third value in first_name
label=df['first_name'][2])
# Set the y axis label
ax.set_ylabel('Score')
# Set the chart's title
ax.set_title('Test Subject Scores')
# Set the position of the x ticks
ax.set_xticks([p + 1.5 * width for p in pos])
# Set the labels for the x ticks
ax.set_xticklabels(df['first_name'])
# Setting the x-axis and y-axis limits
plt.xlim(min(pos)-width, max(pos)+width*4)
plt.ylim([0, max(df['pre_score'] + df['mid_score'] + df['post_score'])] )
# Adding the legend and showing the plot
plt.legend(['Pre Score', 'Mid Score', 'Post Score'], loc='upper left')
plt.grid()
plt.show()