Python 11_ list comprehension

     import numpy as np

     numbers = [1, 2, 3, 4, 5]

     print(numbers)

     numbers2 = []

     for i in range(1,6):

          numbers2.append(i)

          print(numbers2)

# List comprehension

     numbers3 = [n for n in range(1,6)]

     print(numbers3 )

실행결과

[1]

[1, 2, 3, 4, 5]

[1, 2]

[1, 2, 3, 4, 5]

[1, 2, 3]

[1, 2, 3, 4, 5]

[1, 2, 3, 4]

[1, 2, 3, 4, 5]

[1, 2, 3, 4, 5]

[1, 2, 3, 4, 5]

# 2, 4, 6, 8, 10

     even = [2 * n for n in range (1,6)]

     print(even)

실행결과

[2, 4, 6, 8, 10]

# 1, 4, 9, 16, 25

     squares = [n **2 for n in range(1,6)]

     print(squares)

실행결과

[1, 4, 9, 16, 25]

# 난수 10개 배열

     randoms = [np.random.randint(0, 101)for x in range(10)]

     print(randoms)

실행결과

[94, 66, 87, 92, 23, 78, 44, 72, 36, 22]

# 2, 4, 6, 8, 10

     even2 = []

     for n in range(1,11):

          if n%2 ==0:

               even2.append(n)

     print(even2)

실행결과

[2, 4, 6, 8, 10]

# 2, 4, 6, 8, 10

     even3 = [n for n in range(1,11) if n%2 == 0]

     print(even3)

실행결과

[2, 4, 6, 8, 10]

# 주사위 2개를 던졌을 때의 경우의 수

# (1,1), (1,2).. (1,6),

# (2,1) ..(2,6)

# ...

# (6,6)

     dice1 = [] # 빈 리스트 생성

     for x in range(1,7):

          for y in range(1,7):

               dice1.append((x, y)) #(x,y) tuple를 리스트에 추가

     print(dice1)

실행결과

[(1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6), (2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (3, 1), (3, 2), (3, 3), (3, 4), (3, 5), (3, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)]

     dice2 = [(x,y) for x in range(1,7) for y in range(1,7)]

     print(dice2)

실행결과

[(1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6), (2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (3, 1), (3, 2), (3, 3), (3, 4), (3, 5), (3, 6), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)]

# (1,1)

# (2,1), (2,2)

# (3,1), (3,2), (3,3)

# ...

# (x,y) if x >= y

     dice3 = []

     for x in range(1,7):

          for y in range(1,7):

               if x>=y:

                    dice3.append((x,y))

     print(dice3)

실행결과

[(1, 1), (2, 1), (2, 2), (3, 1), (3, 2), (3, 3), (4, 1), (4, 2), (4, 3), (4, 4), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)]

dice4 = [(x,y)

     for x in range(1,7)

          for y in range(1,7)

               if x>=y]

     print(dice4)

실행결과

[(1, 1), (2, 1), (2, 2), (3, 1), (3, 2), (3, 3), (4, 1), (4, 2), (4, 3), (4, 4), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6)]

# 시험점수(0 ~ 100) 10개를 가지고 있는 리스트

     scores = [np.random.randint(0,101) for _ in range(10)]

     print(scores)

실행결과

[37, 12, 72, 9, 75, 5, 79, 64, 16, 1]

# 평균보다 높은 점수들의 리스트

     mean = np.mean(scores)

     above_mean = []

     for s in scores:

          if s > mean:

               above_mean.append(s)

     print(above_mean)

실행결과

[72, 75, 79, 64]

list comprehension에 IF절 적용하기 : 3항 연산자

def identity(x, y):

     result = 0

     if x==y:

          result = 1

     else:

          result = 0

     return result

위와 아래는 동일한 함수이다.

def identity(x, y):

     return result = 1 if x == y else 0 # 3항 연산자

# result에 if 조건을 만족하면 1, 만족하지 않으면 0을 저장한다.