Generating random student marks and plotting to graph in Python

Q. Write a program that does the following

• define a function to generate 1000 integer number randomly between 0 and 100, and save them in a file call it 'data.dat'.
• define a function to read the file contents and count the number of numbers that fall in each range and put the results in a list:

List Name	From	To
A	90	100
B	80	89
C	70	79
D	60	69
E	50	59
F	0	49

• Use a bar chart to show the list contents.

Solution in python 3

from random import randint
from collections import defaultdict, OrderedDict
import matplotlib.pyplot as plt

# function to generate 1000 integer number randomly between 0 and 100, and save them in a file called 'data.dat'
def generatorZ():
    # randint to generate number between
    # list comprehension to loop 1000 times
    numbers = [randint(0, 101) for i in range(1000)]
    # create a data.dat file
    with open("data.dat", "w") as f:
        # convert our integers to strings
        temp = [str(i) for i in numbers]
        # join our array of strings
        f.write("\n".join(temp))
    # return our array of numbers
    return numbers

# function to read the file contents and count the number of numbers that fall in each range and put the results in a list


def graderZ():
    # defining our grades
    grades = {
        "A": [90, 101],
        "B": [80, 90],
        "C": [70, 80],
        "D": [60, 70],
        "E": [50, 60],
        "F": [0, 50],
    }
    # create an empty integer dictionary such as {'key1':0, 'key2':0, 'key3':0}
    groups = defaultdict(int)

    # read our earlier created data.dat file
    with open("data.dat", "r") as f:
        # split lines to array of number string
        numbers = f.read().splitlines()
        # convert number string to integers
        numbers = [int(i) for i in numbers]
        # loop through each numbers
        for i in numbers:
            # loop through each grades
            for key, value in grades.items():
                # if number falls under a particular group ,example group "A" increment as such groups["A"] +=1
                if i in range(value[0], value[1]):
                    groups[key] += 1
                    # continue to next number on finding the correct group, this will save time
                    # example - if it finds the number 84 fall under group "B" it will not check further if it falls under group "C", "D", "E" & "F"
                    continue
        # sort our dictionary called groups
        groups = OrderedDict(sorted(groups.items()))
        # return count of each group
        return groups

# use our number generator function
numbers = generatorZ()
# use our grades counter function
grades = graderZ()

# using matplotlib to plot our data
fig = plt.figure()
ax = fig.add_axes([0,0,1,1])
groups = list(grades.keys())
students = list(grades.values())
ax.bar(groups,students)
plt.show()

Example output