[python] 문법09

#
# 콘솔파입출력: 리다이렉션 기능
#
a=[1,2,3,4,5,6]
for i in range(len(a)-1):
    print(a[i],",",end="")
print(a[len(a)-1])

python a.py > a.txt
python a.py >> a.txt

#
#
#
a=[]
for i in range(3):
    b = input()
    a.append(b)
print(a)
#다음과 같이 키보드에서 입력
1
2
3
>>>['1', '2', '3']

----- a.txt -----
1
2
3
----------------
python a.py < a.txt
>>>['1', '2', '3']

#
# 파일에 출력
#

#
# 텍스트 파일 - 기본
#
----------------------------------------
file = open("test.txt", "w")
file.write('hello')
file.write("\n")
file.write('world')
file.write("\n")
file.close()

file=open("test.txt", "r")
lines = file.read()
file.close()
print(lines)

#
msg = ["HELLO\n", "WORLD\n", "안녕\n"]
file = open("test.txt", "w", encoding='utf-8')
file.writelines(msg)
file.close()

file = open("test.txt", "r", encoding='utf-8')
line = file.readline()
while line != '':
    print(line, end='')
    line = file.readline()
file.close()

print()
file = open("test.txt", "r", encoding='utf-8')
lines = file.readlines()
file.close()
line = ''
for line in lines:
    print(line, end='')

----------------------------------------
리스트에 있는 값 저장
----------------------------------------
import csv
f=open('a.csv', 'w',newline='')
writer=csv.writer(f, delimiter=',')
writer.writerow([1,2,3])
writer.writerow([4,5,6])
f.close()
----a.csv----
1, 2, 3
4, 5, 6
-------------

import csv
f=open('a.csv', 'r', encoding='utf-8')
reader=csv.reader(f)
for line in reader:
    print(line)
f.close()

>> 실행결과
['1', '2', '3']
['4', '5', '6']
----------------------------------------
data=[1,2,3]
with open('a.csv', 'w', newline='') as csvfile:
    writer = csv.writer(csvfile, delimiter=',')
    writer.writerow(data)
----------------------------------------
import numpy as np
data = np.loadtxt('a.csv', delimiter=',', dtype=np.float32)
print(data)

>> 실행결과
[[1. 2. 3.]
 [4. 5. 6.]]
----------------------------------------
f = open('a.csv', 'r')
lines = f.read()
print(lines)
f.close()
>> 실행결과
1,2,3
4,5,6
----------------------------------------
#
# 이진파일
#
import pickle
colors = [1, 2, 3, 4]
pickle.dump(colors, open('colors.txt', 'wb'))
mycolors = pickle.load(open('colors.txt', 'rb'))
print(mycolors)
----------------------------------------

#

# 원그리기 / 파이 추정(근사)하기
#

# 무식한 방법으로 근사하기 ~ 몬테카를로 방법

#

import random

import math

import csv

xset = []

yset = []

def generateSamples(size):

    xset.clear()

    yset.clear()    

    for i in range(size):

        x = random.random()

        y = random.random()

        xset.append(x)

        yset.append(y)

def isInsideCircle(x, y):

r = 0.5

distance = (x - 0.5)*(x - 0.5) + (y - 0.5)*(y - 0.5) - r*r

if (distance >= 0.0):

return False

else:

return True

def estimagePi():

    area_square = 10000

    area_circle = 0

    generateSamples(area_square)

    dataset=[0, 0]

    with open('a.csv', 'w', newline='') as csvfile:

        points = csv.writer(csvfile, delimiter=',')

        for i in range(len(xset)):

            x= xset[i]

            y = yset[i]

            if (isInsideCircle(x, y)==True):

                dataset[0]=x

                dataset[1]=y

                '''points.writerow(dataset)'''

                area_circle = area_circle + 1

    return 4.0 * area_circle / area_square    

pi = estimatePi()

print("pi = %10.9f"%(pi))

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