Matplotlib - when plotting time it puts decimal zeros after the seconds

Question

Here is the plot I have currently:

The 'time' strings I import are like this: 08:12:46, so I would like to cut the zeros at the end, but I can't seem to find the problem. Also, is there a way to show the floats on the Y axis in the exponential format, which is the one I am importing from the csv?

I just started to look into matplotlib and numpy for work, so if you have some advice it would be fantastic.

Thank you in advance!

import numpy as np
import datetime as dt
import matplotlib
import matplotlib.pyplot as plt
import matplotlib.animation as animation
from matplotlib import style

print(plt.style.available)

style.use('ggplot')

fig = plt.figure()
ax1 = fig.add_subplot(1,1,1)

def animate(i):
    graph_data = open('C:\\Users\\arzuffi pc test\\Desktop\\VMI WIP - Copia (2)\\Cycle info\\_Current Cycle.csv','r').read()
    #graph_data = open('C:\\Users\\arzuffi pc test\\Desktop\\Visual Machine Interface Alpha 1.4.3\\Cycle info\\_Current Cycle.csv','r').read()
    lines = graph_data.split('\n')
    xs = []
    ys = []
    skip = 0
    for line in lines:        
        if skip < 7:
            skip += 1
        else:                
            if len(line) > 1:
                time, cycle, pc, pd, co, hv, cr, ph, gd_volt, gd_amp, gd_power, eva_amp, eva_volt, p_rpm, p_amp, r1_rpm, r1_amp, r2_rpm, r2_amp, hmdso, gas, ahc, diff_l, diff_r = line.split(';')
                #x, y = line.split(';')
                print(time)
                print(pc)
                xs.append(dt.datetime.strptime(time,'%H:%M:%S'))#.date())
                ys.append(pc)

        #print(i)
    #xs = matplotlib.dates.date2num(xs)    
    print(xs)    
    if len (xs) > 100:
        xs = xs[-100:]
    if len (ys) > 100:
        ys = ys[-100:] 
    ax1.clear()
    ax1.plot(xs, ys)
    plt.gcf().autofmt_xdate()

ani = animation.FuncAnimation(fig, animate,interval = 1000)
plt.show()

these are the data:

Answer 1

You can specify the format to be used as follows:

xs = matplotlib.dates.date2num(xs)    # You need to keep this line

hfmt = matplotlib.dates.DateFormatter('%H:%M:%S')
ax1.xaxis.set_major_formatter(hfmt)
ax1.plot(xs, ys)   # You have this already

This would give you an output as follows: