Problem with stacked area chart, keeps showing up percent stacked area chart?

Question

So I've spent about 10 hours on this simple task already, I'm out of patience. I'm unable to get the chart I want.

What I want:

What I get:

Yes I am using percentages, but I do not want my chart to be full, I just want the percentages to be stacked one on top of eachother.

My code:

plt.figure()
plt.stackplot(unique_years, my_percentages[:, 0], my_percentages[:, 1],my_percentages[:, 2], labels=['Petrol','Diesel', 'Hybrid'])
plt.legend(loc='upper left')
plt.show()

The my_percentage is a numpy table with 3 columns named 0,1 and 2, each representing a type of fuel as a percentage.

Unique_years is an array for each unique year (1997-2020).

Can anybody please help? I am desperate lol

Answer 1

You need to put the three lists into a list:

from matplotlib import pyplot as plt
import numpy as np

unique_years = np.arange(1997, 2021)
my_values = np.random.rand(len(unique_years), 5)
my_percentages = 100 * my_values / my_values.sum(axis=1, keepdims=True)
plt.stackplot(unique_years, [my_percentages[:, 0], my_percentages[:, 1], my_percentages[:, 2]])
plt.show()

Or you could just transpose the percentages array:

from matplotlib import pyplot as plt
from matplotlib.ticker import PercentFormatter
import numpy as np

unique_years = np.arange(1997, 2021)
my_values = np.random.rand(len(unique_years), 5)
my_percentages = 100 * my_values / my_values.sum(axis=1, keepdims=True)
plt.stackplot(unique_years, my_percentages.T[:3], labels=['fuel a', 'fuel b', 'fuel c'], colors=plt.cm.Set2.colors[:3])
plt.margins(x=0)
plt.gca().yaxis.set_major_formatter(PercentFormatter(100))
plt.legend(loc='upper left', bbox_to_anchor=[1.02, 1.02])
plt.tight_layout()
plt.show()