python基礎技巧綜合訓練題2

1，判斷乙個字串中的每乙個字母是否都在另乙個字串中，可以利用集合的特性來解，集合的元素如果存在，再次更新(update) 是新增不進集合的，那麼集合的長度還是跟原來一樣，如果新增進去，集合長度就會增加

>>> a = '

ghost
'>>> b = '
hello, can you help me install ghost windows xp system
'>>> b_set =set( b )
>>>b_set.update( list( a ) )
>>> print len( b_set ) ==len( set( b ) )
true
>>> a = '
abcostg
'>>>b_set.update( list( a ) )
>>> print len( b_set ) ==len( set( b ) )
false
>>>

2，如果是多個字元呢?

#

!/usr/bin/python
#coding:utf-8
#str_list = [ 'abc', 'ghost', 'hello' ]
str_list = [ '
abc', '
ghost
', '
hellox']
target_str = "
abcdefghijklopqrst
"target_str_set =set( target_str )
for val in
str_list:
target_str_set.update( val )
print len( target_str_set ) == len( set( target_str ) )

3，統計出現次數最多的字元

ghostwu@ghostwu:~/python/tmp$ python str3.py[('

f', 7), ('
s', 5), ('
a', 4), ('
j', 4), ('
k', 3), ('
h', 2), ('
3', 2), ('
1', 2), ('
2', 2), ('
d', 1), ('
l', 1), ('
4', 1), ('
;', 1)]
ghostwu@ghostwu:~/python/tmp$ cat str3.py 
#!/usr/bin/python
#coding:utf-8
str = '
askfjkjasf1234fasdfasfsh;lkjfhjf123
'l = ( [ ( key, str.count( key ) ) for key in
set( str ) ] )
l.sort( key = lambda item : item[1], reverse =true )
print
lghostwu@ghostwu:~/python/tmp$

這裡有個lambda表示式, key指定按哪個鍵排序， item是形參，代表當前的元組，item[1]，那就是取元組中第2項，這裡就是字串的次數，reverse = true,從高到低排序 .

4，統計this模組中, be, is, than,三個單詞的出現次數

ghostwu@ghostwu:~/python/tmp$ !p

python statics.py [('
be', 3), ('
is', 10), ('
than
', 8)]
ghostwu@ghostwu:~/python/tmp$ cat statics.py 
#!/usr/bin/python
#coding:utf-8
import
osthis_str = os.popen( "
python -m this
").read()
this_str = this_str.replace( '
\n', ''
)l = this_str.split( '')
print [ ( x, l.count( x ) ) for x in ['
be', '
is', '
than
'] ]
ghostwu@ghostwu:~/python/tmp$

os.popen( "python -m this" ).read  讀出命令列python -m this  模組的執行結果到乙個字串中

5，用位移運算子，換算b, kb, mb之間的轉換關係

ghostwu@ghostwu:~/software$ ls -l sogoupinyin_2.2.0.0102_amd64.deb 

-rw-rw-r-- 1 ghostwu ghostwu 22852956 2月   2 14:36 sogoupinyin_2.2.0.0102_amd64.deb
ghostwu@ghostwu:~/software$ ls -lh sogoupinyin_2.2.0.0102_amd64.deb 
-rw-rw-r-- 1 ghostwu ghostwu 22m 2月   2 14:36 sogoupinyin_2.2.0.0102_amd64.deb
ghostwu@ghostwu:~/software$ python
python 2.7.12 (default, dec  4 2017, 14:50:18) 
[gcc 5.4.0 20160609] on linux2
type 
"help
", "
", "
credits"or
"license
"for
more information.
>>> size = 22852956
>>> print
"%s kb
" % ( size >> 10)
22317kb
>>> print
"%s mb
" % ( size >> 20)
21mb
>>>

6，把列表中的值，連線成字串

>>> a = [10, 20, 30, 1, 2, 3]

>>> s =str( a )
>>>s
'[10, 20, 30, 1, 2, 3]
'>>>type( s )
'str
'>
>>> s[1:-1]
'10, 20, 30, 1, 2, 3
'>>> s.replace( '
, ', '', s[1:-1] )
traceback (most recent call last):
file 
"", line 1, in
typeerror: an integer 
isrequired
>>> s[1:-1].replace( '
, ', '')'
102030123
'>>>

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