#lists and tuples
#list fragmentation
d[x:y:z] #z is the step size
# sequence add
[1,2,3]+[4,5,6]
[1,2,3,4,5,6]
'hello '+'world'
'hello world'
[1,2,3]+'aa' #Error
#multiplication
'python'*5
'pythonpythonpythonpythonpython'
[None]*10 #Initialize a sequence of 10 lengths
#membership
a in b #f returns boolean
# use string
# String objects are immutable
website[-3:]='dom' #Error
#string formatting
format='Hello,%s %s enough for ya?'
values=('world','hot')
print format % values #Hello,world hot enough for ya?
"""sequences will only be parsed as one value, only dictionaries and tuples can format more than one value
If there is a % in the text, use %% to escape """
format='%.3f' #Format floating-point numbers, accurate 3 digits
format='%10.3f' #Format floating point number, width 10, precise 3 digits
format='%.5s' #The first five characters
'%.*s' % (5,'guido van rossum') # *, width will be read in tuple, guido
#0 padding
'%010.2f'%pi
'0000003.14'
# left align
'%-10.2f'%pi
'3.14'
#Add a space before positive numbers for alignment
print('% 5d'%10)+'\n'+('% 5d'%-10)F
10
-10
# Whether positive or negative, add a sign
print('%+5d'%10)+'\n'+('%+5d'%-10)F
+10
-10
print '-'*10 #----------
#template string
from string import Template
s=Template('$x,glorious $x!')
s.substitute(x='slurm') #slurm,glorious slurm!
s=Template('It`s ${x}tastic!') #replace part of the word
"""
If there is $ in the text, use $$ to escape
The argument to substitute() can be a dictionary
The method safe_substitute() will not report an error due to the wrong use of $
"""
#tuple
'%s plus %s equals %s'%(1,1,2)
1 plus 1 equals 2
#string method
#find
'asdfghjkl'.find('asd') #Return 0, if no query is found, return -1, otherwise return the leftmost index
subject.find('aaa',1) #Provide starting point
subject.find('aaa',1,10) #Provide starting point and ending point, including the first and not the second
#join
seq=[1,2,3,4,5]
sep='+'
sep.join(seq) #Error report, only a list of strings can be connected
seq=['1','2','3','4','5']
sep.join(seq)
'1+2+3+4+5'
dirs='','usr','bin','env'
'/'.join(dirs)
'/usr/bin/env'
print 'C:'+'\\'.join(dirs)
C:\usr\bin\env
#lower lowercase
'ABC'.lower()
'abc'
#capitalization
"that`s all folks".title()
"That`S All Folks"
import string
string.capwords("that`s all folks")
"That`s All Folks"
#replace
'This is a test'.replace('is','eez')
'This ezz a test'
#split
'1+2+3+4+5'.split(+)
['1','2','3','4','5']
#strip remove spaces or characters from both sides
'asd '.strip()
'asd'
#translate is the same as the replace method, but only processes a single character. The advantage is that multiple replacements can be performed at the same time, which is sometimes much more efficient than replace
from string import makestrans
table=makestrans('cs','kz')
len (table)
256
table[97,123]
'abkdefghijklmnopqrztuvwxyz' #c and s are replaced by k and z, this table can be used as the parameter of translate
makesrans('','')[97,123]
'abcdefghijklmnopqrstuvwxyz'
'this is an incredible test'.translate(table)
'thiz iz an inkredible'
#translate(table[,s]) The second character is used to specify the delete character
'this is an incredible test'.translate(table,' ')
'thizizaninkredible'
#dictionary
#dict() function
items=[('name','Gumby'),('age',42)]
d=dict(items)
d
['age':42,'name','Gumby']
d['name']
'Gumby'
#dict() can create a dictionary with keyword arguments
d=dict(name='Gumby',age=42)
#If dict() takes no arguments, create an empty dictionary
#Common methods
len(d) #return the number of key-value pairs
d[k] #return the value corresponding to the k key
d[k]=v #Associate the value to the key
del d[k] #delete the item of key k
k in d #Check if there is an item with key k in d
#dictionary format string
phonebook
{'Beth':'9102','Alice':'2341','Cecil':'3258',}
"Cecil`s phone number is %{Cecil}s"%phonebook
"Cecil`s phone number is 3258"
#dictionary method
#clear
d.clear() #Blue empty dictionary, the return value is none
x={}
y=x
x['key']='value'
and
{'key':'value'}
x.clear() #Operate on objects
and
{}
#copy和deepcopy
from copy import deepcopy
d={}
d['name']=['Alfred','Bertrand']
c=d.copy()
dc=deepcopy(d)
d[name].append('Clive')
c
{'name':{'Alfred','Bertrand','Clive'}}
dc
{'name':{'Alfred','Bertrand'}}
#fromkeys initialize dictionary
{}.fromkeys(['name','age'])
{'age':None,'name':None}
dict.fromkeys(['name','age'],'(unknow)') #Define the default value, which can be called directly on the dictionary type dict
{'age':'(unknow)','name':'(unknow)'}
#get
d={}
print d['name'] #error
print d.get('name')
None
d.get('name','N/A') #define the default value
'N/A'
#has_key() is equivalent to k in d, python3 does not contain this function
d={}
d.has_key('name')
False
#items and iteritems
d={'a':'aa','b':'bb','c':'cc'}
d.items()
[('a','aa'),('b','bb'),('c','cc')]
it=d.iteritems() #return iterator
list(it)
[('a','aa'),('b','bb'),('c','cc')] #Indeterminate order