The use of Python bisec module

I. brief introduction to bisec module:

Python's bisec module is a built-in module, which is used to maintain the sequence table. It uses dichotomy to sort and insert

What are bisec's methods:

# Import bisect package first
import bisect
print(dir(bisect))
# Output results:
['__builtins__', '__cached__', '__doc__', '__file__',
 '__loader__', '__name__', '__package__', '__spec__',
 'bisect', 'bisect_left', 'bisect_right', 'insort',
 'insort_left', 'insort_right']

Among the above methods, in addition to magic methods, other methods are explained in detail:

Bisec: returns the subscript of the inserted element in the list

my_list = [1, 3, 5, 7, 9]
result = bisect.bisect(my_list, 6)
print(result)

# Output results:3 Indicates the subscript of the insert element in the list

bisect_left: the element is found to the left by default, and the subscript inserted to the left is returned.

my_list = [1, 3, 5, 7, 9]
result = bisect.bisect_left(my_list, 6)
print(result)

# Output results: 3 with bisect Method

Bisec  right: opposite to bisec  left

my_list = [1, 5, 3, 9, 7]
result = bisect.bisect_right(my_list, 6)
print(result)

# Output results: 3 

Insert: inserts elements in the list to the correct location

# If the elements in the list are ordered
my_list = [1, 3, 5, 7, 9]
bisect.insort(my_list, 2)
print(my_list)

# Output results:[1, 2, 3, 5, 7, 9]

# If the elements in the list are unordered, they are inserted to the far right by default.
my_list = [2, 3, 1, 5, 7, 4]
bisect.insort(my_list, 6)
print(my_list)

# Output results:[2, 3, 1, 5, 7, 4, 6]

Insert? Left: insert value on the left, return value None

my_list = [1, 3, 5, 7, 9]
bisect.insort_left(my_list, 2)
print(my_list)

# Output results:[1, 2, 3, 5, 7, 9]

Insert? Right: insert value on the right, return None

my_list = [1, 3, 5, 7, 9]
bisect.insort_right(my_list, 6)
print(my_list)

# Output results:[1, 3, 5, 6, 7, 9]

Insert ﹐ left and insert ﹐ right: just insert in different position

II. Use scenarios:

For example, a chestnut should be graded according to the student's performance. The student's performance (0-100) should be graded into (ABCDEF):

General operation:

def grade(score):
    if score < 60:
        return 'F'
    elif score < 70:
        return 'E'
    elif score < 80:
        return 'D'
    elif score < 90:
        return 'C'
    elif score < 100:
        return 'B'
    else:
        return 'A'


scores = [59, 60, 72, 82, 85, 90, 98, 100]
result = [grade(item) for item in scores]
print(result)

# The output is as follows:
['F', 'E', 'D', 'C', 'C', 'B', 'B', 'A']

To use bisec:

• For example, the dividing point of students' grades is [60, 70, 80, 90, 100], and the grade is' fedba '

  def grade(score, points=[60, 70, 80, 90, 100], grade="FEDCBA"):
      item = bisect.bisect(points, score)
      return grade[item]
  
  
  scores = [101, 60, 72, 82, 85, 90, 98, 100]
  result = [grade(item) for item in scores]
  print(result)
  
  # The output results are as follows:
  ['A', 'E', 'D', 'C', 'C', 'B', 'B', 'A']
  

• Store member points for grading:

  def grade(score, points=[60, 70, 80, 90, 100], grade="FEDCBA"):
      item = bisect.bisect(points, score)
      print(grade[item])
      return grade[item]
  
  
  scores = [1000, 2000, 3000]
  names = ['Ordinary member', 'Intermediate Member', 'Senior member', 'VIP']
  values = [999, 1999, 2999, 3001]
  print([grade(item, points=scores, grade=names) for item in values])
  
  # The output results are as follows:['Ordinary member', 'Intermediate Member', 'Senior member', 'VIP']