Matplotlib time series graph with 3 Y-Axes on right side of graph

Question

I am using matplotlib to graph 3 time series. I want all 3 y-axes to be plotted on the right side of the graph. However I am unable to get one of the y-axis values to plot on the right side, only it's axis label.

Here is my code:

import numpy as np 
import matplotlib.pyplot as plt 
import matplotlib as mpl 
import datetime as dt
import matplotlib.dates as mdates
from matplotlib.ticker import ScalarFormatter, FormatStrFormatter
from matplotlib import ticker

# Set date range for graph 
df_ratios=df_ratios.loc['2017-06':'2021-12']

#-------------------------------------------------------------------
#For all Matplotlib plots, we start by creating a figure and an axes.
#-------------------------------------------------------------------
# subplot for plotting figure
fig, ax = plt.subplots()

#Similar to fig=plt.figure(figsize=(12,6))
fig.set_figwidth(12) 
fig.set_figheight(6)

# Graph title
#############
fig.suptitle('Inventory-to-Sales Ratios by Industry',fontsize=20)

# LABELS: Set x label which is common / set left y-axis label / set labelcolor and labelsize to the left Y-axis
###############################################################################################################
ax.set_xlabel('Monthly: Jun 2017 - Dec. 2021') 
ax.set_ylabel('Manufacturers I/S Ratio', color='red',size='x-large') 
ax.tick_params(axis='y', labelcolor='red', labelsize='large') 
ax.spines["right"].set_visible(True)

# Left Y-Axis: Mfg IS ratio on left Y-axis
###########################################
ax.plot(df_ratios.index, df_ratios['mfg_is_ratio'], color='red',linewidth=5.0)
ax.set_ylim(1.25,1.8)  
ax.yaxis.set_major_locator(ticker.MultipleLocator(0.10))  

ax.yaxis.set_label_position('right')
ax.yaxis.set_ticks_position('right')
ax.spines["right"].set_position(("axes", 1.0))    # Set second Y-axis 10% away from existing Y axis

# RIGHT Y-Axis labels: twinx sets the same x-axis for both plots / set right y-axis label / set labelcolor and labelsize to the right Y-axis
############################################################################################################################################
ax_1 = ax.twinx() 
ax_1.set_ylabel('Wholesalers I/S Ratio', color='blue', size='x-large') 
ax_1.tick_params(axis='y', labelcolor='blue',labelsize='large') 

# FIRST Right Y-Axis plot: Wholesale IS ratio
#############################################
ax_1.plot(df_ratios.index, df_ratios['whole_is_ratio'], color='blue',linewidth=5.0) 
ax_1.spines["right"].set_position(("axes", 1.08))    # Set second Y-axis 10% away from existing Y axis
ax_1.set_ylim(1.15,1.75)  
ax_1.yaxis.set_major_locator(ticker.MultipleLocator(0.10))  

# SECOND Right Y-Axis: Sum of Mfg+Wholesale ratios
##################################################
ax_2=ax.twinx()
ax_2.set_ylabel('Wholesalers Inventories', color='green', size='x-large') 
ax_2.spines["right"].set_position(("axes", 1.18))    # Set second Y-axis 10% away from existing Y axis
ax_2.set_ylim(2.60,3.25)  
ax_2.plot(df_ratios.index, df_ratios['totals'], color='green',linewidth=5.0) 
ax_2.tick_params(axis='y', labelcolor='green',labelsize='large') 

# Show graph:
#############
plt.show()

Here is the result:

How do I get the red y-axis values (manufacturers i/s ratio) to plot on the right side of the graph?

Answer 1

The problem is, when twinx() is used. From the source code documentation:

Create a new Axes with an invisible x-axis and an independent y-axis positioned opposite to the original one (i.e. at right).

To reverse this, just use ax.yaxis.tick_right() after all twinx() calls. For example right before plt.show().

Red ticks should be now placed on the right side.