List 실습 예제

List 사용

Split 사용 방법

data = "AI-Engineering-202100-김재웅"

splitter = "-"

splitter 정해주기

dataList = data.split(splitter)

print(dataList)

['AI', 'Engineering', '202100', '김재웅']

dataList

['AI', 'Engineering', '202100', '김재웅']

print안써도 확인 가능!

List 원소 접근

print(dataList[0])
print(dataList[1])
print(dataList[2])
print(dataList[3])

AI
Engineering
202100
김재웅

print로 접근

for i in range(len(dataList)):
    print(dataList[i], type(dataList[i]))

AI <class 'str'>
Engineering <class 'str'>
202100 <class 'str'>
김재웅 <class 'str'>

for문으로 접근

for elem in dataList:
    print(elem)

AI
Engineering
202100
김재웅

더 간단하게 접근

dataList[2] = 202105
for i in range(len(dataList)):
    print(dataList[i], type(dataList[i]))
dataList

AI <class 'str'>
Engineering <class 'str'>
202105 <class 'int'>
김재웅 <class 'str'>





['AI', 'Engineering', 202105, '김재웅']

길이 보기

print(len(dataList))
print(len(dataList[0]))
print(len(dataList[1]))
print(len(dataList[3]))

4
2
11
3

원소 추가하기

append(원소) : 마지막에 원소 추가

insert(index, 원소) : 인덱스자리에 원소 추가

dataList.append("국어")
dataList

['AI', 'Engineering', 202105, '김재웅', '국어']

dataList.append(100)
dataList

['AI', 'Engineering', 202105, '김재웅', '국어', 100]

dataList.insert(4, 95)
dataList.insert(4, "수학")
dataList

['AI', 'Engineering', 202105, '김재웅', '수학', 95, '국어', 100]

원소 삭제하기

del List[index] - 인덱스 위치 원소 삭제

List.remove(원소) : 원소를 찾아서 삭제

del dataList[3]
dataList

['AI', 'Engineering', 202105, '수학', 95, '국어', 100]

dataList.remove("국어")
dataList.remove(100)
dataList

['AI', 'Engineering', 202105, '수학', 95]

List 이어붙이기

List.extend(dataList)

dataList.extend(dataList)
dataList

['AI', 'Engineering', 202105, '수학', 95, 'AI', 'Engineering', 202105, '수학', 95]

mathIdx = dataList.index("수학")
dataList

['AI', 'Engineering', 202105, '수학', 95, 'AI', 'Engineering', 202105, '수학', 95]

sorting은 숫자들 끼리 가면 사용 가능

워밍업 문제

HelloList = ["hello", "안녕", "gonigiwa", "nihao", "ssawadicap"]
for i in range(len(HelloList)):
    print(HelloList[i])

hello
안녕
gonigiwa
nihao
ssawadicap

HelloList.insert(1, "Привет")
HelloList.remove("gonigiwa")
HelloList.remove("nihao")
HelloList

['hello', 'Привет', '안녕', 'ssawadicap']

실습 문제1

Int_List = [1, 3, 5, 2, 7, 4]

def min_max(Int_List):
    min_value = Int_List[0]
    max_value = Int_List[0]
    for idx in range(1, len(Int_List)):
        if min_value > Int_List[idx]:
            min_value = Int_List[idx]
        if max_value < Int_List[idx]:
            max_value = Int_List[idx]
    
    return (min_value, max_value)

min_value, max_value = min_max(Int_List)
min_value, max_value

(1, 7)

실습 문제2

def trim_mean(Int_List):
    
    a, b = min_max(Int_List)
    
    Int_List.remove(a)
    Int_List.remove(b)
    sum = 0
    for idx in range(len(Int_List)):
        sum += Int_List[idx]
    
    return (sum / len(Int_List))

trim_mean(Int_List)

3.5

실습 문제3

Int_List = [1, 3, 5, 2, 7, 4]

def remove_odd(Int_List):
    odd_list = []
    for i in range(len(Int_List)):
        if Int_List[i] % 2 == 0:
            odd_list.append(Int_List[i])
    
    return odd_list

remove_odd(Int_List)

[2, 4]

Int_List = [1, 3, 5, 2, 7, 4]

def even_List(Int_List):
    even_list = Int_List[:]
    for idx in range(len(Int_List)):
        if Int_List[idx] % 2 == 1:
            even_list.remove(Int_List[idx])
    return even_list

even_List(Int_List)

[2, 4]

import math
import matplotlib.pyplot as plt
from sklearn.linear_model import LinearRegression
from sklearn.preprocessing import PolynomialFeatures
from sklearn.pipeline import Pipeline
import numpy as np

x = np.linspace(-2*math.pi, 4*math.pi, 40)
x = x.reshape(-1, 1)
y = np.sin(x)
plt.scatter(x, y)   # 오리지널 데이터 플롯

lr = LinearRegression()
# polynomial feature를 사용하여 x의 차원을 올린다.
poly_feat = PolynomialFeatures(degree=10)

pipeline = Pipeline([("polynomial_features", poly_feat),
                         ("linear_regression", lr)])
pipeline.fit(x, y)


x_test = np.linspace(-2*math.pi, 4*math.pi, 40)
x_test = x_test.reshape(-1, 1)
plt.plot(x_test, pipeline.predict(x_test))
#plt.plot(x_test, pipeline.predict(x_test[:, np.newaxis]))
plt.show()