Python 3.4 Part2
讀檔
f= open("rw_test", "w") # w代表寫入，w+則是沒有檔案的話會自動新增
f.write("Hello 123")
f.close()
f = open ("rw_test", "r") # r代表讀取
f.read()
Output: 'Hello 123'
載入模組
範例1：載入模組
import random # 載入random模組
print(random.randint(2,29)) # 使用其中的randint函式
from random import randinr # 載入random的randint模組
print(randint(2,29)) # 使用時不用寫一大串
範例2：讀組網頁
from urllib.request import urlopen # 載入讀取網頁模組
data = urlopen("http://www.cs.pu.edu.tw/~ylyang/vcs_git.html").read()
str = data.decode() # 轉成utf-8格式
print (str)
範例3：寄信功能
import smtplib # 載入smtp模組
server = smtplib.SMTP('ms.example.com.tw') # 設定smtp server
server.set_debuglevel(1) # 將寄信每個步驟列出來
server.sendmail('[email protected]', '[email protected]', "HAHAHAHAAAA") # Mail內容(只寫body部份)
server.quit()
import smtplib # 載入smtp模組
from email.mime.text import MIMEText # 載入MIMEText模組
from email.header import Header # 載入Header模組
msg = MIMEText('嘿嘿嘿嘿嘿','plain','utf-8') # 設定MIMEText內容，並指令utf-8格式
server = smtplib.SMTP('ms1.example.com.tw')
server.set_debuglevel(1)
server.sendmail('[email protected]', '[email protected]', msg.as_string())
server.quit()
系統操作
範例1：列出目錄中的檔案
import os # 載入os模組
cwd = os.getcwd() # 取得目前檔案，並存成cwd串列
print ('Current directory is:')
print (os.listdir(cwd))
Output:
Current directory is: ['.ipynb_checkpoints', 'images', 'rw_test', 'py_class_1.ipynb', 'py_class_2.ipynb', 'mydata.pickle', 'python_class_3.ipynb', 'child.py', 'test_mk_dir', 'output']
範例2：列出目錄中的檔案與目錄，及其目錄下的內容(遞迴方式)
import os
for dirname, dirs, files, in os.walk('.'): # os.walk代表遞迴方式
print ('dirname: ', dirname+' dirs: ', dirs,'\nfiles: ', files ,end='\n\n')
Output:
dirname: . dirs: ['.ipynb_checkpoints', 'images', 'test_mk_dir', 'output'] files: ['rw_test', 'py_class_1.ipynb', 'py_class_2.ipynb', 'mydata.pickle', 'python_class_3.ipynb', 'child.py'] dirname: ./.ipynb_checkpoints dirs: [] files: ['py_class_1-checkpoint.ipynb', 'py_class_2-checkpoint.ipynb', 'python_class_3-checkpoint.ipynb'] dirname: ./images dirs: [] files: ['py1.png', 'py3.png', 'py2.png'] dirname: ./test_mk_dir dirs: [] files: [] dirname: ./output dirs: ['subdir1'] files: [] dirname: ./output/subdir1 dirs: ['subdir2'] files: [] dirname: ./output/subdir1/subdir2 dirs: ['subdir3'] files: [] dirname: ./output/subdir1/subdir2/subdir3 dirs: [] files: []
範例3：較格式化的顯示
import os
for dirname, dirs, files, in os.walk('.'):
for f in files:
print('file', os.path.join(dirname, f))
Output:
file ./rw_test file ./py_class_1.ipynb file ./py_class_2.ipynb file ./mydata.pickle file ./python_class_3.ipynb file ./child.py file ./.ipynb_checkpoints/py_class_1-checkpoint.ipynb file ./.ipynb_checkpoints/py_class_2-checkpoint.ipynb file ./.ipynb_checkpoints/python_class_3-checkpoint.ipynb file ./images/py1.png file ./images/py3.png file ./images/py2.png
範例4：刪除檔案
for dirname, dirs, files in os.walk('.'):
for f in files:
if f == '.DS_Store':
path = os.path.join(dirname, f)
os.remove(path) #移除檔案
範例5：檢查檔案或目錄是否存在
path = 'output'
if os.path.exists(path): # 檢查是否存在
if os.path.isdir(path): # 檢查是否為目錄
print('{0} is a dir'.format(path))
else:
print ('{0} is not a dir.'.format(path))
else:
print('{0} do not exits!'.format(path))
範例6：新增目錄
path = 'output'
path1 ='test_mk_dir'
os.mkdir(path1) # 建立單一目錄
path2 = os.path.join('output', 'subdir1', 'subdir2', 'subdir3') # 設定階層目錄
os.makedirs(path2) # 直接建立樹狀目錄
程序(process)操作
子程序訊息回覆
範例1：subprocess.call()
產生子程序執行指令，若子程序完成會回傳0，有錯誤則回傳大於0的數值。
import subprocess
rc = subprocess.call(["ls","-l"])
print(rc)
Output: 0
範例2：subprocess.check_call()
同subprocess.call()功能，但若回傳值不為0，會顯示錯誤訊息以便Debug用
subprocess.check_call("exit 1", shell=True)
Output:
---------------------------------------------------------------------------
CalledProcessError Traceback (most recent call last)
<ipython-input-23-49abebf0c09f> in <module>()
----> 1 subprocess.check_call("exit 1", shell=True)
2
3 #shell = True這個參數主要是，python會先再開一個shell出來，並且一整串字串丟給shell來解釋並執行
4 #基本上有些指令是屬於shell特有的像是 cd <目錄的路徑名稱>就是其中一個例子
/usr/local/lib/python3.4/subprocess.py in check_call(*popenargs, **kwargs)
559 if cmd is None:
560 cmd = popenargs[0]
--> 561 raise CalledProcessError(retcode, cmd)
562 return 0
563
CalledProcessError: Command 'exit 1' returned non-zero exit status 1
範例3：subprocess.check_output()
將收到子程序執行後的輸出。並如範例2，若回傳值大於0會產生錯誤訊息。
import subprocess
a=subprocess.check_output(["ls", "-a"])
print(a)
Output: b'.\n..\n.ipynb_checkpoints\nchild.py\nimages\nmydata.pickle\noutput\npy_class_1.ipynb\npy_class_2.ipynb\npython_class_3.ipynb\nrw_test\ntest_mk_dir\n'
產生子程序：Popen()
範例1：
import subprocess
child = subprocess.Popen(["ping","-c","5","www.google.com"]) # 產生子程序，讓它ping google5次
print(child.pid)
print("parent process")
範例2：等待子程序完成
import subprocess
child = subprocess.Popen(["ping","-c","5","www.google.com"])
child.wait()
print("parent process")
以下是對於子程序可進行的操作
child.poll() # 檢查child process狀態
child.kill() # 終止child process
child.send_signal() # 向child process發送signal
child.terminate() # 透過發送terminate(SIGNAL 15)訊號的方式終止child process
標準輸入、輸出、管線
import subprocess
child1 = subprocess.Popen(["ls","-l"], stdout=subprocess.PIPE) # child1的輸出存在stdout中。
child2 = subprocess.Popen(["wc"], stdin=child1.stdout,stdout=subprocess.PIPE)
# wc在unix 系統是一個可以計算行數，byte數以及字數的指令
out = child2.communicate() # communicate可讀取PIPE中的值。
print(out)
Output: (b' 10 83 573\n', None)
輸入指令讓子程序執行
from subprocess import Popen, PIPE
command1 =input("請輸入shell指令:") # 讓使用者輸入指令
p = Popen(command1, shell=True ,stdout=PIPE) # 輸出結果放在stdout中
result = p.stdout.read()
print (result)
Output:
請輸入shell指令:whoami
b'nalant\n'