CODEWITHSUNDEEP
pythonmatplotliblabel
N.C.C.P.
N.C.C.P.

Reputation: 13

Stacked Bar Chart Labeling using Matplotlib

Hello fellow programmers,

For a project I want to generate a stacked bar chart plot. I was succesful at this. However, I want to add a label to every bar to indicate the size of each bar. I read the demo on the fairly new added function to matplotlib called the bar label: Bar Label Demo.

The solution I tried to come up with is as follows:

# hard-coded data
dist_lst = [
    [0, 0, 0, 1, 1, 0], [0, 0, 0, 1, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 4, 1, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 1], 
    [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 14, 0, 1], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 0, 0, 0], [0, 1, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0], 
    [0, 0, 0, 0, 0, 0], [0, 0, 0, 1, 0, 0]
]

# defined colors
colors = [
    "#e6194b", "#3cb44b", "#ffe119", "#4363d8", "#f58231",
    "#911eb4", "#46f0f0", "#f032e6", "#bcf60c", "#fabebe",
    "#008080", "#e6beff", "#9a6324", "#fffac8", "#800000",
    "#aaffc3", "#808000", "#ffd8b1", "#000075", "#808080",
    "#ffffff", "#000000", "#eb5b01", "#db8c62", "#f58b7a",
    "#288C00",
]

i = 0
lst = np.array(dist_lst)
fig, ax = plt.subplots()
ax.bar(range(6), lst[0], edgecolor="black", color=colors[0])
sum_arr = lst[0]
for data in lst[1:]:
    i += 1
    ax.bar(range(6), data, bottom=sum_arr, edgecolor="black", color=colors[i])
    sum_arr += data

ax.legend(list(range(1, len(lst))), title="families", ncol=2, bbox_to_anchor=(1, 1))

# Adding size labels
for c in ax.containers:
    ax.bar_label(c, label_type="center")

My apologies if it is poorly readable but for now it works... sort off. The issue being it generates a plot containing also the zero values resulting in clutter.

Stacked bar chart

How do I resolve the issue of these zero values being plotted? Also, if anyone has tips for the color pallete, I'm all ears because I would like to make this as readablefriendly as possible.

Thank you for your time!

Upvotes: 1

Views: 1848

Answers (1)

Alex
Alex

Reputation: 7045

When you iterate to add the labels at the end the objects held in c are instances of matplotlib.container.BarContainer. These have an attribute datavalues which are used for labelling unless you provide other labels to matplotlib.axes.Axes.bar_label with the parameter labels.

Therefore, setting empty strings for 0 values allows you to control what is added:

# Adding size labels
for c in ax.containers:
    # Create a new list of labels
    labels = [a if a else "" for a in c.datavalues]
    ax.bar_label(c, labels=labels, label_type="center")

Which, in combination with your code, produces:

enter image description here

Upvotes: 1

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