How to check that i is 0 in io.BytesIO().seek(i)?

Question

I make lineplot to send for sending to Telegram. First sending is ok.

Second time I get error: BadRequest: File must be non-empty

How to check what i = 0 (position of cursor) in seek(i)?

sns.lineplot(x=x, y=y);
plt.title('test plot');

plot_object = io.BytesIO()
plt.savefig(plot_object)
plot_object.seek(0)

plot_object.name = 'test_plot.png'
plt.close()

bot.sendPhoto(chat_id, plot_object)

Answer 1

You can use plot_object.tell() to check cursor position before and after seeking.

Test Code:

import io
import matplotlib.pyplot as plt
import seaborn as sns

x = [1, 2, 3, 4, 5]
y = [2, 4, 1, 5, 2]

sns.lineplot(x=x, y=y)
plt.title('test plot')

plot_object = io.BytesIO()
plt.savefig(plot_object)

print("Before seek:", plot_object.tell()) # check cursor position
plot_object.seek(0) # seek to the start 
print("After seek:", plot_object.tell())

#plt.show() 
plt.close()

Output:

Before seek: 25771
After seek: 0