Main thread not in main loop error in threading module - python-3.x

Question

import time
import datetime as dt
import urllib.request
from bs4 import BeautifulSoup
import matplotlib.pyplot as plt
import matplotlib.animation as Animation
from matplotlib import style
import matplotlib
import csv
import threading
style.use('fivethirtyeight')
fig = plt.figure()
def usd_in_bitcoin():
try:
resp = urllib.request.urlopen("https://bitcoinwisdom.com/")
except Exception as e:
print(e)
text = resp.read()
soup = BeautifulSoup(text, 'html.parser')
intermediate = soup.find('tr', {"id": "o_btcusd"})
ans = intermediate.find('td', {'class': 'r'})
return ans.contents[0]
def write_to_file(interval):
while True:
value = str(usd_in_bitcoin())
unix_time = str(time.time())
print(unix_time, value)
with open('bitcoin_usd.csv', 'a+') as file:
file.write(unix_time)
file.write("," + str(value))
file.write('\n')
time.sleep(interval)
def animate(i):
with open('bitcoin_usd.csv') as csv_file:
readcsv = csv.reader(csv_file, delimiter=',')
xs = []
ys = []
for row in readcsv:
if len(row) > 1:
x, y = [float(s) for s in row]
xs.append(dt.datetime.fromtimestamp(x))
ys.append(y)
print(len(xs))
dates = matplotlib.dates.date2num(xs)
# print(dates)
fig.clear()
plt.plot_date(dates, ys)
def plotting():
ani = Animation.FuncAnimation(fig, animate, interval=1000)
plt.show()
def main():
# plotting()
b = threading.Thread(name='making graph', target=plotting)
# a = threading.Thread(name='updating_csv', target=write_to_file, args=(5,))
# a.start()
b.start()
if __name__ == '__main__':
main()
In the above block of code, I am trying to plot the value of a bitcoin in usd by using scraping and then putting the value in a csv file.
Then I read the csv file to plot the graph.
Both plotting and scraping seem to work fine but if I do both of them simultaneously, I am getting an error saying main thread not in main loop. I searched a lot but was not able to solve this problem

Answer 1

The problem here is with the sequence of lines in main()
Try this:
def main():
a = threading.Thread(name='updating_csv', target=write_to_file, args=(5,))
a.start()
b = threading.Thread(name='making graph', target=plotting)
b.start()
plotting()