Some easy-to-forget points in the Python Learning Manual (the first three parts)

1.ubuntu allows the Python script to run directly:
test.py file (suffix can be saved)
#!/usr/bin/python
Print (' wwwww ')

sudo chmod +x./test.py (sudo chmod 755./2)
Execute./test.py can
Can be added as a shortcut:
sudo ln-s/home/zh/Desktop/test.py/usr/bin/test
Execute test

2. Remove 0-20, can be divisible by 3 number (list parsing)
>>> [x for x in range (0,20) if x% 3 ==0]
[0, 3, 6, 9, 12, 15, 18]
>>>

3. Run a script
>>> a= "{1:1,2:2, ' 1 ': 22}"
>>> Eval (a)
{' 1 ': 22, 1:1, 2:2}
>>> B=eval (a)
>>> type (b)
<type ' Dict ' >

>>> eval (' list (' qqqqqqqqqqq ') ')
[' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ', ' Q ']

4. Character and number conversion
>>> chr (115)
' s '
>>> ord (' C ')
99

5. String formatting
>>> ' aaaa%s bbbbb%s CCCCC '% ($)
' AAAA 1 bbbbb 2 CCCCC '
>>>
>>> t= ' {}+{}={} '. Format (+/-)
>>> T
' 1+2=3 '
>>>

6. Dictionary and List parsing
>>> Dict ([(2,2)])
{1:1, 2:2}
>>> zip ([1,2,3],[1,2,3])
[(1, 1), (2, 2), (3, 3)]
>>> {a:b*2 for (A, b) in [(1, 1), (2, 2), (3, 3)]}
{1:2, 2:4, 3:6}
>>>

7. Achieve Python3-like printing
>>> from __future__ import print_function
>>> for line in open ('/home/zh/desktop/Notes '):p rint (line, ')

8. Conditional judgment in an assignment statement
>>> c= ' 1111122222333334444455555 '
>>> d=c[:5]+ ' # ' +c[5:] If Len (c) <5 Else (c[:5]+ ' # ' +c[5:10]+ ' # ' +c[10:] If Len (c) ==15 Else (c[:5]+ ' # ' +c[5:10]+ ' # ' +c[10:15]+ ' # ' +c[15:] If Len (c) ==20 Else (c[:5]+ ' # ' +c[5:10]+ ' # ' +c[10:15]+ ' # ' +c[15:20]+ ' # ' +c[20:] If Len (c) ==25 Else 3)))
>>> D
' 11111#22222#33333#44444#55555 '
>>>

9.zip and Map,enumerate
>>> A
[1, 2, 3]
>>> b
[5, 6, 7]
>>> Zip (A, B)
[(1, 5), (2, 6), (3, 7)]
>>> type (Zip (b))
<type ' list ' >
>>> Map (chr,a)
[' \x01 ', ' \x02 ', ' \x03 ']
>>> p=[' 1 ', ' 2 ', ' 3 ']
>>> Enumerate (p)
<enumerate Object at 0x7f93e36688c0>
>>> type (enumerate (p))
<type ' Enumerate ' >
>>> for II in Enumerate (p):p rint (ii)
...
(0, ' 1 ')
(1, ' 2 ')
(2, ' 3 ')
>>> N=enumerate (P)
>>> Next (N)
(0, ' 1 ')
>>>

5. Get Help
DIR (SYS)
Help (SYS)

Some easy-to-forget points in the Python Learning Manual (the first three parts)