How to remove empty x-axis coordinates in Matplotlib - python-3.x

Question

I'm developing in Python using the pandas, numpy and matplotlib modules, to paint various subplots of a dataframe, using the following code:
import pandas as pd
import numpy as np
from matplotlib import pyplot as plt
import matplotlib.ticker as ticker
data = {'Name': ['Status', 'Status', 'HMI', 'Allst', 'Drvr', 'CurrTUBand', 'RUSource', 'RUReqstrPriority', 'RUReqstrSystem', 'RUResReqstStat', 'CurrTUBand', 'DSP', 'SetDSP', 'SetDSP', 'DSP', 'RUSource', 'RUReqstrPriority', 'RUReqstrSystem', 'RUResReqstStat', 'Status', 'Delay', 'Status', 'Delay', 'HMI', 'Status', 'Status', 'HMI', 'DSP'],
'Value': [4, 4, 2, 1, 1, 1, 0, 7, 0, 4, 1, 1, 3, 0, 3, 0, 7, 0, 4, 1, 0, 1, 0, 1, 4, 4, 2, 3],
'Id_Par': [0, 0, 0, 0, 0, 0, 10, 10, 10, 10, 10, 0, 0, 22, 22, 28, 28, 28, 28, 0, 0, 38, 38, 0, 0, 0, 0, 0]
}
signals_df = pd.DataFrame(data)
def plot_signals(signals_df):
# Count signals by parallel
signals_df['Count'] = signals_df.groupby('Id_Par').cumcount().add(1).mask(signals_df['Id_Par'].eq(0), 0)
# Subtract Parallel values from the index column
signals_df['Sub'] = signals_df.index - signals_df['Count']
id_par_prev = signals_df['Id_Par'].unique()
id_par = np.delete(id_par_prev, 0)
signals_df['Prev'] = [1 if x in id_par else 0 for x in signals_df['Id_Par']]
signals_df['Final'] = signals_df['Prev'] + signals_df['Sub']
# Convert and set Subtract to index
signals_df.set_index('Final', inplace=True)
# Get individual names and variables for the chart
names_list = [name for name in signals_df['Name'].unique()]
num_names_list = len(names_list)
# Creation Graphics
fig, ax = plt.subplots(nrows=num_names_list, figsize=(10, 10), sharex=True)
plt.xticks(color='SteelBlue', fontweight='bold')
# Matplotlib's categorical feature to convert x-axis values to string
x_values = [-1, ]
for name in all_names_list:
x_values.append(signals_df[signals_df["Name"] == name]["Value"].index.values[0])
x_values.append(len(signals_df) - 1)
x_values = [str(i) for i in sorted(set(x_values))]
print(x_values)
for pos, (a_, name) in enumerate(zip(ax, names_list)):
# Creating a dummy plot and then remove it
dummy, = ax[pos].plot(x_values, np.zeros_like(x_values))
dummy.remove()
# Get data
data = signals_df[signals_df["Name"] == name]["Value"]
# Get values axis-x and axis-y
x_ = np.hstack([-1, data.index.values, len(signals_df) - 1])
y_ = np.hstack([0, data.values, data.iloc[-1]])
# Plotting the data by position
ax[pos].plot(x_.astype('str'), y_, drawstyle='steps-post', marker='*', markersize=8, color='k', linewidth=2)
ax[pos].set_ylabel(name, fontsize=8, fontweight='bold', color='SteelBlue', rotation=30, labelpad=35)
ax[pos].yaxis.set_major_formatter(ticker.FormatStrFormatter('%0.1f'))
ax[pos].yaxis.set_tick_params(labelsize=6)
ax[pos].grid(alpha=0.4, color='SteelBlue')
# Labeling the markers with CAN-Values
for i in range(len(y_)):
if i == 0:
xy = [x_[0].astype('str'), y_[0]]
else:
xy = [x_[i - 1].astype('str'), y_[i - 1]]
ax[pos].text(x=xy[0], y=xy[1], s=str(xy[1]), color='k', fontweight='bold', fontsize=12)
plt.show()
plot_signals(signals_df)
I'm having trouble when names get repeated, using Matplotlib's categorical feature and converting x-axis values to string; taking into consideration the focus of the answer; this is what is bringing me:
I have been trying to change the pandas conditions, since it is the condition that I am using in this line: x_values.append(signals_df[signals_df["Name"] == name]["Value"].index.values[0]) and when I print the variable x_values it brings me the wrong indices: ['-1', '0', '2', '3', '4', '5', '6', '11', '12', '20', '27'] and I can't make it work well.
I expect to achieve is a graph like the following:
The yellow shading is the jumps that it must make on the x-axis and that it are not painting on the y-axis. Thank you very much to anyone who can help me, any comments help.

Answer 1

I leave this answer for possible searches later for someone with the same topic. I found my error, the way I was handling the for loop was not correct, I replaced it and modified it as follows:
# Matplotlib's categorical feature and to convert x-axis values to string
x_values = [-1,]
x_values + = (list (set (can_signals.index)))
x_values = [str (i) for i in sorted (x_values)]
This now allows to bring up the graph as below: