When plotting from a CSV file using matplotlib, 0 values on X, Y axis are not plotting and I need them to be plotted

Question

The 0 values from my CSV file are not plotting, any idea as to why this is happening and how I can ensure they are plotted?

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

columns = np.array(["Ast", "Gls"]) 
df = pd.read_csv(r"document.csv", usecols=columns) 
print("Contents in csv file:\n", df)  

colors =(["red"])   
size = ([500])  

plt.scatter(df.Ast, df.Gls, c=colors, s=size, alpha=0.5, cmap='viridis') 
plt.show()

Contents in csv file:
     Gls  Ast
0     2    1
1     4    5
2     0    3
3     1    9
4     1    1
5     4    2
6     1    1
7     5    4
8     7    4
9     4    1
10    5    6
11    4    1
12    0    1
13    2    2
14    3    0
15    1    0
16    0    2
17    4    5
18    0    1
19    4    3
20    2    5
21   14   11
22    4    1
23    3    6
24    7    1
25    2    5
26    9    3

For example all the results with figures above zero are plotted.

Answer 1

This is the plot I'm getting with your code and data:

You can clearly see that all points are accounted for, even the ones in which X or Y is zero.

There are a few points having a darker red color: it means that there are 2 or more points sharing the same location.