Change axis x scale in a bar chart

Question

I find myself graphing by means of bars a Dataframe that I have called barras that contains data from 2017 to 2022, for months. In each month there are 3 columns with data denominated as % PRINCIPAL, % APORTES y % E. I wanted to be able to graph the bars since 2009, even if there is no data, and that only the 1st and 6th months of each month appear on the x-axis labels, but I can't do it.

This is the Dataframe:

% PRINCIPAL  % APORTES       % ΔE
FECHA                                     
2017-03    25.974253  42.430129  31.595618
2017-04   131.728602  27.057582 -58.786184
2017-05   144.069530  17.564611 -61.634142
2017-06   116.492102  25.948196 -42.440299
2017-07    95.677079  42.383666 -38.060745
             ...        ...        ...
2022-05    86.728444  46.208640 -32.937084
2022-06    87.980394  58.643608 -46.624002
2022-07    73.873644  53.591839 -27.465483
2022-08    72.113597  44.375137 -16.488734
2022-09    52.777619  79.301887 -32.079506

And this is my code to do the graphic:

barras = pd.concat([I['% PRINCIPAL'],I['% APORTES'],I['% ΔE']], axis=1)
barras.index = pd.to_datetime(barras.index).strftime('%Y-%m')
barras.plot(kind="bar",stacked=True, color = ['b','g','r'], edgecolor='black', width=1, alpha=0.77, figsize=(16,8))
plt.title('PORCENTAJES DE CAUDAL EN TRAMO I')
plt.ylabel("Caudal (%)")
plt.xlabel('Fecha')
plt.legend(loc='best')
plt.savefig("BLOQUE I.png", bbox_inches="tight", dpi=160)

Result:

I want the same graphic but since 2009, and with the x-axis label each six moths.

I would like to get something like this (I've done it with photoshop):

Do you want to bin your data? [pandas.cut](https://pandas.pydata.org/docs/reference/api/pandas.cut.html) — Cpt.Hook, Mar 15 '23 at 11:32
No, I only want to see the graphic since 2009, although I know that there are not data from 2009 to 2017. And in the other hand I would like to see only the label each six month, not all label that are so much, and since 2009 it label will be so small. — Guille GL, Mar 15 '23 at 11:38
For the number labels maybe [this](https://stackoverflow.com/questions/12608788/changing-the-tick-frequency-on-the-x-or-y-axis) helps, for the range try [`xlim`](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.xlim.html) — Cpt.Hook, Mar 15 '23 at 12:12

Brener Ramos · Accepted Answer · 2023-03-20T22:44:48.470

You can concatenate your dataframe with another one containing the rest of the dates you are interested in and then plot that.

import pandas as pd 
import numpy as np 
import matplotlib.pyplot as plt

# Create dummy data 
dates = pd.date_range('2/2017', '8/2022', freq='M')
values = np.random.uniform(-100, 100, (len(dates), 3))
barras = pd.DataFrame(values, columns=['% PRINCIPAL',  '% APORTES', '% ΔE'], index=dates)

# Create new dataframe with 0s for dates starting from 2009
add_dates = pd.date_range('1/2009', barras.index[0], freq='M')[:-1]
df_0 = pd.DataFrame(0, columns=['% PRINCIPAL',  '% APORTES', '% ΔE'], index=add_dates)

# Concatenate everything into a single dataframe
barras = pd.concat([df_0, barras])

# Plot
fig, ax = plt.subplots(1,1, figsize=(16,8))
barras.set_index(barras.index.strftime('%Y-%m')).plot(
    kind="bar",
    stacked=True,
    color = ['b','g','r'],
    edgecolor='black',
    width=1,
    alpha=0.77,
    ax=ax
    )

new_ticks = ax.get_xticks()[barras.index.month.isin([1,1+6])]
ax.set_xticks(new_ticks)

plt.title('PORCENTAJES DE CAUDAL EN TRAMO I')
plt.ylabel("Caudal (%)")
plt.xlabel('Fecha')
plt.legend(loc='best')
plt.savefig("BLOQUE I.png", bbox_inches="tight", dpi=160)

EDIT: Now the code shows all the data and the temporal line is right.

Thanks u very much! Its works! But I only have one question, and is that the frequency of data show is six moths, bur i want to plot all data, but only show the label each six moth... I think that I did not explain good in the post. Thanks you again! — Guille GL, Mar 16 '23 at 09:00
And the x-axis label of your graphic is wrong, it good that show every six months, but the temporal line don't follow a logical orden... — Guille GL, Mar 16 '23 at 09:07
I fixed the x axis in the code so plot equally spaced dates and also it is plotting all the data now. — Brener Ramos, Mar 20 '23 at 22:45

Change axis x scale in a bar chart

1 Answers1