·
set in the python What does it mean?
set is a set of numbers, the disorder, the content can not be repeated, created by calling the set ():
|
1
|
>>> s = set([
'A'
,
'B'
,
'C'
])
|
For the meaning of a set of access that would only see if an element in this collection there, observing case sensitive:
|
1
|
>>>
print
'A'
in sTrue>>>
print
'D'
in sFalse
|
Also to traverse through for:
|
1
|
s = set([(
'Adam'
, 95), (
'Lisa'
, 85), (
'Bart'
, 59)])
for
x in s:
print
x[0],
':'
,x[1]>>>Lisa : 85Adam : 95Bart : 59
|
When added by add and remove, delete elements (holding not repeated), an additive element, with the SET add () method
|
1
|
>>> s = set([1, 2, 3])>>> s.add(4)>>>
print
sset([1, 2, 3, 4])
|
If the element to add already exists in this set, add () does not complain, but not added to the list:
|
1
|
>>> s = set([1, 2, 3])>>> s.add(3)>>>
print
sset([1, 2, 3])
|
When you delete elements in this set, remove set with the () method:
|
1
|
>>> s = set([1, 2, 3, 4])>>> s.remove(4)>>>
print
sset([1, 2, 3])
|
set in, remove () If you remove the element does not exist will get an error:
|
1
|
>>> s = set([1, 2, 3])>>> s.remove(4)Traceback (most recent call last): File
"<stdin>"
, line 1, in <module>KeyError: 4
|
So if we want to determine whether an element in a number of different conditions in line with the set is the best choice, the following example:
|
1
|
months = set([
'Jan'
,
'Feb'
,
'Mar'
,
'Apr'
,
'May'
,
'Jun'
,
'Jul'
,
'Aug'
,
'Sep'
,
'Oct'
,
'Nov'
,
'Dec'
,])x1 =
'Feb'
x2 =
'Sun'
if
x1 in months:
print
'x1: ok'
else
:
print
'x1: error'
if
x2 in months:
print
'x2: ok'
else
:
print
'x2: error'
>>>x1: okx2: error
|
Furthermore, computational efficiency is higher than the set list.