Plot 幅度 [dB] 与频率 [deg] 与 matplotlib.pyplot python 其中 Mag 和 Freq 是两个列表

Question

# plotting Magnitud vs. Freq
figure1 = plt.Figure(figsize=(5,4), dpi=100)
ax1 = figure1.add_subplot(111)
ax1.plot(freq, mag_S11, color = 'r')
# ax1.set_ylim([-75, 50])
# ax1.set_xlim([0.0, 30.0])
scatter = FigureCanvasTkAgg(figure1, root) 
scatter.get_tk_widget().pack(side=tk.RIGHT, fill=tk.BOTH)
ax1.legend(['S11']) 
ax1.set_xlabel('Frequency [GHz]')
ax1.set_title('Magnitude[dB] Vs. Frequency')

My freq and mag_S11 are 2 lists of more than 200 elements, the problem is I'm not getting the graph behavior I want. Am I plotting it correctly or the values are wrong?

This is what I'm getting:

This is what I want:

Any help would be really appreciated.

Answer 1

That is because plot connects the dots. You want to either use ax1.scatter(...) with the current data or ax1.plot(...) with the data sorted so that x increases. Using

 freq, mag_S11 = sorted([freq, mag_S11], key=lambda x: x[0])

should sort both datasets by increasing frequency and let the plot work nicely.