Python – How to animate a scatterplot plot of Pandas data using matplotlib

I’m currently trying to animate a scatterplot of monthly data saved in the pandas data frame. So far, I’ve made a loop to generate a graph one by one. Now I want to join them in a GIF (or MP4 that I don’t care about). Is there an easy way to use the mathplotlibs animation feature? I can’t understand how to slice data through FuncAnimation loops. So far, I’ve done it :

time = df.monat.unique()
for i in time:
    dft = df[(df.monat == i) & (df.xcol < 4000)]
    plt.scatter(x=dft['xcol'],
            y=dft['ycol'],
            s=dft['scol'] / 25,
            c=dft['clr'],
            linewidth=0,
            alpha=0.8)
    plt.title('Title ' + str(i), fontsize=10)
    plt.xlabel('x label', fontsize=9)
    plt.ylabel('y label', fontsize=9)
    legend1_line2d = list()
    for val in clrdict.values():
        legend1_line2d.append(mlines. Line2D([0], [0],
            linestyle='none',
            marker='o',
            alpha=0.6,
            markersize=6,
            markeredgecolor=None,
            markeredgewidth=0,
            markerfacecolor=val))
    legend1 = plt.legend(legend1_line2d,
             names,
             frameon=False,
             numpoints=1,
             fontsize=8,
             loc='upper right') 
    plt.show()

I came up with it myself :

Generate an empty plot (graph). As before, all unique time values are stored in a series (time). A simple counter (i) helps generate the correct piece of data (dft) for each month in the update function (df.monat == value from series “time”). Call the update function multiplied by anim. The value of the frame parameter in FuncAnimation (frames=len(time)).

Hopefully, this will help others (I’ve found that most of the explanations for matplotlib FuncAnimation use random numbers – not specific pandas columns):

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.lines as mlines
import matplotlib.animation as anim

...

time = df.monat.unique()    
fig = plt.figure()
i = 1

def update(i):
        plt.clf()
        dft = df[(df.monat == time[i]) & (df.xcol < 4000)]
        plt.scatter(x=dft['xcol'],
                    y=dft['ycol'],
                    s=dft['scol'] / 25,
                    c=dft['clr'],
                    linewidth=0,
                    alpha=0.8)
        plt.title('Title ' + str(time[i]), fontsize=10)
        plt.xlabel('x label', fontsize=9)
        plt.ylabel('y label', fontsize=9)
        plt.xlim(0, 900)  # fixed dimensions x
        plt.ylim(-5, 100) # fixed dimensions y 
        legend1_line2d = list()
        for val in clrdict.values():
            legend1_line2d.append(mlines. Line2D([0], [0],
                    linestyle='none',
                    marker='o',
                    alpha=0.6,
                    markersize=6,
                    markeredgecolor=None,
                    markeredgewidth=0,
                    markerfacecolor=val))
        legend1 = plt.legend(legend1_line2d,
                    names,
                    frameon=False,
                    numpoints=1,
                    fontsize=8,
                    loc='upper right')
        i += 1

ani = anim. FuncAnimation(fig, update, frames=len(time), interval=500)
# plt.show() # this will show the ani over and over
ani.save("test.mp4", dpi=200, fps=1, codec="libx264", bitrate=5000, extra_args=['-pix_fmt', 'yuv420p'])