python中range() 函式的使用
阿新 • • 發佈:2018-12-13
range()函式的使用
- 首先利用help(range)來看一下python中的詳細解釋:
>>>help(range)
>Help on class range in module builtins:
class range(object)
| range(stop) -> range object
| range(start, stop[, step]) -> range object
|
| Return an object that produces a sequence of integers from start (inclusive)
| to stop (exclusive) by step. range(i, j) produces i, i+1, i+2, ..., j-1.
| start defaults to 0, and stop is omitted! range(4) produces 0, 1, 2, 3.
| These are exactly the valid indices for a list of 4 elements.
| When step is given, it specifies the increment (or decrement).
|
| Methods defined here:
|
| __contains__(self, key, /)
| Return key in self.
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[ key].
|
| __gt__(self, value, /)
| Return self>value.
|
| __hash__(self, /)
| Return hash(self).
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __ne__(self, value, /)
| Return self!=value.
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __reduce__(...)
| helper for pickle
|
| __repr__(self, /)
| Return repr(self).
|
| __reversed__(...)
| Return a reverse iterator.
|
| count(...)
| rangeobject.count(value) -> integer -- return number of occurrences of value
|
| index(...)
| rangeobject.index(value, [start, [stop]]) -> integer -- return index of value.
| Raise ValueError if the value is not present.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| start
|
| step
|
| stop
-
作用 產生一系列整數,返回一個range物件
-
語法:
range(start,end,step) range(start,end) range(end) range函式中帶有三個引數:start、end、step。 例如:產生數字0-1的列表:
>>> list(range(0,10,1))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(range(0,10))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> list(range(10))
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
三種情況輸出結果相同 start 起始值(包含),end 終止值(不包含),step 步長。
- range(start,end)——省卻step時,預設步長為1;
- range(end)——省卻step、start時,預設步長為1,起始值為0 注意:step的值不能為0或者浮點數
>>> list(range(2,10,2))
[2, 4, 6, 8]
>>> list(range(2,10,2.5))
Traceback (most recent call last):
File "<pyshell#16>", line 1, in <module>
list(range(2,10,2.5))
TypeError: 'float' object cannot be interpreted as an integer