A, Python% or format should be used to format string?
The new version of Python recommended format.
Python2.6 newly added format syntax support.
3.6 added a new feature f-strings
Python string formatting There are two camps:% and format, what should we choose?
Since the introduction of the format Python2.6 this method after the format string, I think% or format this is simply not a problem.
# Define a coordinate value
c =(250, 250)
#% Use to format
s1 = "enemy coordinates:% s"% c
Obviously the above code will throw a following TypeError:
TypeError: not all arguments converted during string formatting
As the demand for such formatted we need to write the following format for the job:
# Define a coordinate value
c =(250, 250)
Ugly formatting using the% # ...
s1 = "enemy coordinates:% s"% (c,)
And uses the format would not exist the above questions:
# Define a coordinate value
c =(250, 250)
# Use format to format
s2 = "enemy coordinates: {}". format (c)
Obviously, format more convenient than a%.
Python3.6 added in the F-strings :
In[1]: name ="Q1mi"
In[2]: age =18
In[3]: f"My name is {name}.I'm {age}"
Out[3]: "My name is Q1mi.I'm 18"
Second, the use of commonly used format
In[1]: data =["Q1mi", 18]
In[2]: "Name:{0}, Age:{1}".format(*data)
Out[2]: 'Name:Q1mi, Age:18'
In[1]: data ={"name": "Q1mi", "age": 18}
In[2]: "Name:{name}, Age:{age}".format(**data)
Out[2]: 'Name:Q1mi, Age:18'
In[1]: classPerson(object):
...: def__init__(self, name, age):
...: self.name =name
...: self.age =age
...: def__str__(self):
...: return"This guy is {self.name}, {self.age} years old.".format(self=self)
...:
In[2]: p =Person("Q1mi", 18)
In[3]: str(p)
Out[3]: 'This guy is Q1mi, 18 years old.'
In[1]: "{0[0]} is {0[1]} years old.".format(data)
Out[1]: 'Q1mi is 18 years old.'
Often used in conjunction with aligned filling
^, <,> Are centered, left aligned, right aligned, the width of the back
: Back-filled with a number of characters, only one character is not specified, the default is filled with spaces.
In[1]: "{:>10}".format('18')
Out[1]: ' 18'
In[2]: "{:0>10}".format('18')
Out[2]: '0000000018'
In[3]: "{:A>10}".format('18')
Out[3]: 'AAAAAAAA18
A supplementary string comes zfill () Method:
Python zfill () method returns a specified length of the original string right justified, padded with zeros in front.
zfill () method syntax: str.zfill (width)
Parameters width length of the string. Original string right justified, padded with zeros in front.
Returns a string of specified length.
In[1]: "18".zfill(10)
Out[1]: '0000000018'
Accuracy often used in conjunction with type f.
In[1]: "{:.2f}".format(3.1415926)
Out[1]: '3.14'
Wherein an accuracy of .2 represents the length of 2, f denotes a float.
The main band is a, b, d, o, x are binary, decimal, octal, hexadecimal.
In[1]: "{:b}".format(18)
Out[1]: '10010'
In[2]: "{:d}".format(18)
Out[2]: '18'
In[3]: "{:o}".format(18)
Out[3]: '22'
In[4]: "{:x}".format(18)
Out[4]: '12'
In[1]: "{:,}".format(1234567890)
Out[1]: '1,234,567,890'