Grouped bar offsets
position of series k = x + (k - (m + 1) / 2) * width, painted width = m * width
When several series share each category slot. Keep m x width below 1 so the groups stay separated, and restore the category names with plt.xticks.
- x
- Category centres, usually np.arange(number of categories)
- m
- Number of series (bars per group)
- k
- Which series, counting from 1
- width
- Bar width in x-axis units; Matplotlib's default is 0.8
Histogram bin count from np.arange
edges = np.arange(start, stop, step); bins = number of edges - 1 = ceil((stop - start) / step) - 1
Whenever a histogram question gives bin edges rather than a bin count. Remember np.arange excludes its stop value, so push stop past the last edge you want.
- start
- First bin edge, included
- stop
- Excluded upper limit
- step
- Bin width
Pie slice share and angle
share = value / total; percent printed by autopct = 100 * share; angle = 360 * share
For any pie-chart question, and for the argument against pie charts: convert two slices to degrees and show how close they are.
- value
- One category's size, as passed to plt.pie
- total
- Sum of every value in the list
- autopct
- Format string, e.g. '%1.1f%%', that prints the percentage