如何固定第二个y轴的音量范围

Question

My full code:

import matplotlib.pyplot as plt
plt.style.use('ggplot')
import pandas as pd
import numpy as np

path = 'C:\\MyPath\\File1.txt'
dff = pd.read_csv(path, sep=",")
dff.columns = ['Date','Time','Price','Volume']
dff.plot('Time', ['Price', 'Volume'], secondary_y='Volume')
plt.show()

I have a price-volume DataFrame and I am using below syntax to plot Volume in the second y-axis.

dff.plot('Time', ['Price', 'Volume'], secondary_y='Volume')

My data in Volume column ranges from 0-500. When I am plotting it using the above syntax, the second y-axis takes the maximum and minimum of the Volume and adjust the range automatically.

I need to fix the bracket on second y-axis while plotting. I want the range of Volume as 0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500

Sample Data:

       Date        Time      Price     Volume
72612  31/01/2019  15:26:58  135.85    100
72613  31/01/2019  15:27:02  135.90    110
72614  31/01/2019  15:27:03  135.95    140
72615  31/01/2019  15:27:07  135.95    100
72616  31/01/2019  15:27:10  135.85    60
72617  31/01/2019  15:27:11  135.90    150
72618  31/01/2019  15:27:13  135.95    100
72619  31/01/2019  15:27:15  135.95    100
72620  31/01/2019  15:27:18  135.95    30
72621  31/01/2019  15:27:22  135.95    10

Sample image for more clarity

Answer 1

Since you want to control/modify the secondary y-axis tick labels, I would use slightly different approach to plot: plotting one column at a time. Once you plot the secondary y-axis data, you can override the default tick labels by providing a list of desired tick labels. Based on the DataFrame you provided, following is one way to do it

# Read in your dataframe here

ax  = dff.plot('Time','Price')
ax2 = dff.plot('Time','Volume', ax=ax, secondary_y=True)

y_ticks = range(0, 501, 50)
ax2.set_yticklabels(y_ticks)
plt.show()