python知識整理(模塊及continue brak及try異常處理)_6

#!/usr/bin/env python
# -- conding:utf-8 --

import  模塊 
四個方法:

import time 是指 import time 模塊:
這個模塊能夠是 python 自帶,也能夠是本身安裝的, 如 numpy 模塊,就是須要本身安裝;

一、 improt  time

In [17]: import time                    // 能夠print 當地時間:
print(time.localtime())
time.struct_time(tm_year=2019, tm_mon=7, tm_mday=1, tm_hour=13, tm_min=48, tm_sec=55, tm_wday=0, tm_yday=182, tm_isdst=0)

二、improt  time  as t        //  as 後面能夠自定義,表示把time縮寫成 t.
In [2]: import time as t
print(t.localtime())
time.struct_time(tm_year=2019, tm_mon=7, tm_mday=1, tm_hour=13, tm_min=52, tm_sec=0, tm_wday=0, tm_yday=182, tm_isdst=0)

三、from time  import time,localtime      // 只 import 本身想要的功能, 中間用逗號隔開.
from time import time,localtime
print(localtime())
time.struct_time(tm_year=2019, tm_mon=7, tm_mday=1, tm_hour=13, tm_min=56, tm_sec=12, tm_wday=0, tm_yday=182, tm_isdst=0)

四、form time  import  *                  // 輸入模塊的全部功能
from time import *

In [11]: tim
%%time    %%timeit  %time     %timeit   time      timezone

In [13]: print(time())
1561960733.32

In [14]: print(clock())

自建模塊:

[root@fenye2019 ~]# cat m1.py
#!/usr/bin/env python
# --* conding:utf-8 -*-
def printdata(data):
    print('I am m1')
    print(data)
    
調用: 
improt m1
或者
from m1  import  printdata
m1.printdata('python')

import m1

In [6]: m1.printdata('python')
I am m1
python

註釋: linux 使用import 導入模塊/老是錯誤:        ImportError: No module named numpy

須要修改其包的路徑:          // site-apckages
首先查看包/模塊的位置,      // 經過 sys 模塊裏的 path 功能來實現:
import  sys
sys.path
'/usr/lib64/python2.7/site-packages/gtk-2.0',
 '/usr/lib/python2.7/site-packages',
 '/usr/lib/python2.7/site-packages/cloud_init-0.7.6-py2.7.egg',
 '/usr/lib/python2.7/site-packages/IPython/extensions',
臨時修改:   經過 path 功能下的 append 屬性來增長
sys.path.
sys.path.append   sys.path.extend   sys.path.insert   sys.path.remove   sys.path.sort
sys.path.count    sys.path.index    sys.path.pop      sys.path.reverse

sys.path.append('/usr/lib/python2.7/site-packages')

永久修改:
[root@fenye2019 ~]# tail /etc/profile
export PYTHONPATH=/usr/lib64/python2.7/site-packages:/usr/lib/python2.7/site-packages/IPython/extensions
[root@fenye2019 ~]# source  /etc/profile

再次手動寫一個模塊,計算五年的複利本息的模塊:
[root@fenye2019 ~]# cat balance.py
#!/usr/bin/env python
# --*conding:utf-8 -*-
d=float(input('Please enter what is your initial balance: \n'))
p=float(input('Please input what is the interest rate (as a number): \n'))
d=float(d+d*(p/100))
year=1
while year<=5:
    d=float(d+d*p/100)
    print('Your new balance after year:',year,'is',d)
    year=year+1
print('your final year is',d)

運行:
import balance
Please enter what is your initial balance: 
50000                    // 手動輸入本金:   
Please input what is the interest rate (as a number): 
2.4                      // 手動輸入銀行利息:
('Your new balance after year:', 1, 'is', 52428.8)
('Your new balance after year:', 2, 'is', 53687.0912)
('Your new balance after year:', 3, 'is', 54975.581388800005)
('Your new balance after year:', 4, 'is', 56294.9953421312)
('Your new balance after year:', 5, 'is', 57646.07523034235)
('your final year is', 57646.07523034235)

continue &&  break

continue    重複輸入
break       跳出本次循環,執行循環下面的內容

pass     // 表示空字符,什麼也不作.

break    //表示退出本次循環,執行循環外的內容:
如: 當b = 1, 至關於忽略 break 後面的循環內的那部分代碼,
直接運行 循環以外的 語句;

while True:
    b = input('please input number: ')
    if b == '1':
        break
    else:
        pass
    print('to run ......')
print('flnish run')

python 10.py
please input number: 3
to run ......
please input number: 4
to run ......
please input number: 1
flnish run

continue        // 忽略 continue 後面的代碼,而後從新開始循環:
通常用戶從新輸入字符:

while True:
    b = input('Please input number: ')
    if b == '1':
        continue
    else:
        pass
    print('to run ......')
print('flnish run')

python 10.py
please input number: 2
jixunyunx......
please input number: 1
please input number: 1

try  異常處理

file = open('fenye','r')        //文件不存在則會報錯

IOError: [Errno 2] No such file or directory: 'fenye'

加上try 後                 //  輸出的錯誤能夠寫"自定義的內容"

try:
    file = open('fenye',r)
except Exception as e:
    print(e)
#    print('there is no file name as eeeee')          // 這樣自定義內容也能夠,直接打印內容也能夠。

[Errno 2] No such file or directory: 'fenye'

擴展後以下:  
判斷這個文件是否存在並查看,不存在則由用戶選擇是否建立:
第一次運行時,文件不存在存在,則執行except 裏面的語句,由用戶選擇是否建立,選擇 y ,則建立這個文件,並退出:
第二次運行時,文件已存在,則直接執行最後一個else裏的語句:

try:
    file = open('fenye',r+)           //第二次運行寫入文件內容須要些權限 w.
except Exception as e:
    print('There is not file named as fenye')
    response = raw_input('do you want to create new file: ')
    if response == 'y':
        file = open('fenye','w')
    else:
        pass
else:                                         //此處的else同 try 平行:
    file.write('my name is fenye')
    file.close()

cat fenye
my name is fenye

再次擴展: 
假設用戶輸入的是 n ,或者是大寫的 Y/N ,或者是 yes/no   Yes/No 這樣的,也或者是其餘字符如何判斷:

try:
   ...:     file = open('fenye.txt','r+')
   ...: except Exception as e:
   ...:     print('There is not file named as fenye.txt')
   ...:     response = raw_input('do you want to create new file[Yes/No]: ')
   ...:     re = response.lower()
   ...:     if re == 'y' or re == 'yes':
   ...:         file = open('fenye.txt','w')
   ...:     elif re == 'n' or re == 'no':
   ...:         exit
   ...:     else:
   ...:         print('Please input [Yes/No] ......')
   ...: else:
   ...:     file.write('my name is fenye')
   ...:     file.close()

There is not file named as fenye.txt
do you want to create new file[Yes/No]: 
Please input [Yes/No] ......

There is not file named as fenye.txt
do you want to create new file[Yes/No]: y

In [8]: ls

1.sh*  fenye.txt