plt grid ALPHA parameter not working in matplotlib

Question

I have the current function which generates a simple chart in matplotlib but as we see in the image the alpha parameter not seems to work, this happen in vs code, if I test this in a notebook works fine

what i need is the same format in vs code

data:

,hora,id
0,0,10
1,1,3
2,2,2
3,3,3
4,4,5
5,5,3
6,6,11
7,7,32
8,8,41
9,9,71
10,10,75
11,11,70
12,12,57
13,13,69
14,14,50
15,15,73
16,16,47
17,17,64
18,18,73
19,19,54
20,20,45
21,21,43
22,22,34
23,23,27

code:

import pandas as pd
from matplotlib import pyplot as plt

dfhoras=pd.read_clipboard(sep=',')

def questionsHour(dfhoras):        
        x = dfhoras['hora']
        y = dfhoras['id']
        horas=[x for x in range(24)]
        plt.figure(facecolor="w")
        plt.figure(figsize=(15,3))
        plt.rcParams['axes.spines.top'] = False
        plt.bar(x, y,linewidth=3,color="#172a3d")
        plt.xticks(horas,fontweight='bold',color="#e33e31",fontsize=9)
        plt.yticks(fontweight='bold',color="#e33e31",fontsize=9)
        plt.grid(color="#172a3d", linestyle='--',linewidth=1,axis='y',alpha=0.15)
        #aca creo las etiquetas de los puntos
        for x,y in zip(x,y):
                label = "{:.2f}".format(y)
                plt.annotate(label,
                                (x,y),
                                textcoords="offset points",
                                xytext=(0,5),
                                ha='center',
                                fontsize=9,
                                fontweight='bold',
                                color="#e33e31")
        plt.savefig('questions1.png',dpi=600,transparent=True,bbox_inches='tight')
        
questionsHour(dfhoras)

this is the result in vs code

and this is the result in a notebook

user_7758804 · Answer

Make sure the environment packages used by VSCode are updated, as they aren't necessarily the same as those being used by Jupyter.
- Tested in python 3.8.11, pandas 1.3.2, matplotlib 3.4.3
- I was originally testing with matplotlib 3.4.2, which seems to have a bug and would not set weight='bold', so if VSCode is using a different package version, there could be a bug with alpha=0.15.
The OP uses plt.figure(facecolor="w") and plt.figure(figsize=(15,3)), which creates two different figures (not noticeable with inline plots, but two windows will open if using interactive plots). It should be plt.figure(facecolor="w", figsize=(15, 3)).
The following code uses the object oriented approach with axes, which makes sure all methods are applied to the correct axes being plotted.
Plot the dataframe directly with pandas.DataFrame.plot, which uses matplotlib as the default backend, and returns an axes.
Annotations are made using matplotlib.pyplot.bar_label

import pandas as pd

# test data
data = {'hora': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23], 'id': [10, 3, 2, 3, 5, 3, 11, 32, 41, 71, 75, 70, 57, 69, 50, 73, 47, 64, 73, 54, 45, 43, 34, 27]}
df = pd.DataFrame(data)

# plot function
def questionsHour(df):        

    ax = df.plot(x='hora', y='id', figsize=(15, 3), linewidth=3, color="#172a3d", rot=0, legend=False, xlabel='', kind='bar', width=0.75)
    
    ax.set_xticklabels(ax.get_xticklabels(), weight='bold', color="#e33e31", fontsize=9)
    ax.set_yticks(ax.get_yticks())  # prevents warning for next line
    ax.set_yticklabels(ax.get_yticks(), weight='bold', color="#e33e31", fontsize=9)
    
    ax.grid(color="#172a3d", linestyle='--', linewidth=1, axis='y', alpha=0.15)
    
    ax.spines['top'].set_visible(False)
    ax.bar_label(ax.containers[0], fmt='%.2f', fontsize=9, weight='bold', color="#e33e31")

       
questionsHour(df)

plt grid ALPHA parameter not working in matplotlib

1 Answers