7. python string formatting method (1)

7. Python string formatting method (1)

In the previous section, another way to say string formatting in this section is to call format()

  >>> template='{0},{1} and {2}'  
  >>> template.format ('a','b','c')  
  'a,b and c'  
  >>> template='{name1},{name2} and {name3}'  
  >>> template.format (name1='a',name2='b',name3='c')  
  'a,b and c'  
 >>> template='{name1},{0} and {name2}'  
  >>> template.format ('a',name1='b',name2='c')  
  'b,a and c'  
  >>>   

Here's an example from above

1. The replacement location can be marked with the subsetitution

2. The replacement location can be replaced by a name

Let's talk about adding properties to the method

  >>>import sys  
  >>> 'my {1[spam]} runs {0.platform}'.format(sys,{'spam':  
                           'laptop'})  
  'my laptop runs win32'  
  >>>   

  >>> 'my {config[spam]} runs {sys.platform}'.format(sys=sys,config={'spam':'laptop'})  
  'my laptop runs win32'  
  >>>   

In the two examples above, the first reads the string and the second reads the platform property inside sys

Here's another example of using offsets in an expression

  >>> aList=list('abcde')  
  >>> aList  
  ['a', 'b', 'c', 'd', 'e']  
  >>> 'first={0[0]} third={0[2]}'.format (aList)  
  'first=a third=c'  
  >>>   

Note: When using offsets, you can only be positive integers, you can't use negative numbers, you can't use positive integers that represent intervals

  >>> aList=list('abcde')  
    
  >>> aList  
  ['a', 'b', 'c', 'd', 'e']  
  >>> 'first={0[0]} third={0[-1]}'.format (aList)  
  Traceback (most recent call last):  
    File "", line 1, in   
      'first={0[0]} third={0[-1]}'.format (aList)  
  TypeError: list indices must be integers, not str  
  >>> 'first={0[0]} third={0[1:3]}'.format (aList)  
  Traceback (most recent call last):  
    File "", line 1, in   
      'first={0[0]} third={0[1:3]}'.format (aList)  
  TypeError: list indices must be integers, not str  
  >>>