Matplotlib plot multiple lines not working

Question

When I try to dispaly LSTM and RNN models prediction results with the following code:

plt.figure(figsize=(5, 3))

plt.plot(y_test, c="orange", linewidth=3, label="Original values")
plt.plot(lstm_pred, c="red", linewidth=3, label="LSTM predictions")
plt.plot(rnn_pred, alpha=0.5, c="green", linewidth=3, label="RNN predictions")
plt.legend()
plt.xticks(rotation=45)
plt.title("Predictions vs actual data", fontsize=20)
plt.show()

If I plot them one by one, the lines are displayed correctly.

But display all lines in one plot, the lines don't display correctly. Someone knows how to fix it? Thanks.

Answer 1

As mentioned in the comments you need to create a second Y axis. Then you need to merge the legend together

fig, ax1 = plt.subplots()

line1 = ax1.plot(y_test, c="orange", linewidth=3, label="Original values")
line2 = ax1.plot(rnn_pred, alpha=0.5, c="green", linewidth=3, label="RNN predictions")
plt.xticks(rotation=45)
ax2 = ax1.twinx()  # instantiate a second axes that shares the same x-axis
line3 = ax2.plot(lstm_pred, c="red", linewidth=3, label="LSTM predictions")

# added these three lines
lines = line1+line2+line3
labels = [l.get_label() for l in lines]
ax.legend(lns, labels)

plt.title("Predictions vs actual data", fontsize=20)
plt.show()