erDiagram List --> Index: 使用下标访问元素 Index --> NegativeIndex: 使用负数下标 NegativeIndex --> Element: 访问负数下标元素 步骤 下面是一个表格,展示了实现“Python List负数下标”的步骤: 操作步骤及代码示例 步骤1:创建一个Python List 首先,我们需要创建一个Python List,让
tup1 = (10, 3, 4, 22, 1) print(tup1[10]) # gives an error as the index is only up to 4 输出 IndexError: tuple index out of range 例4 tup1 = (10, 3, 4, 22, 1) print(tup1[1+3]) # the expression inside the square brackets results in an integer index 4. Hence, we...
What if you want to print the last character of a string but you don’t know how long it is?You can do that usingnegative indexes. In the example above, we don’t know the length of the string, but we know that the word ‘text’ plus the exclamation sign take five indices, so w...
index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ """ T.index(value, [start, [stop]]) -> integer -- return first index of value. Raises ValueError if the value is not present. ""
of negative indexes (if the class wishes to emulate a sequence type) is up to the __getitem__() method. If key is of an inappropriate type, TypeError may be raised; if of a value outside the set of indexes for the sequence (after any special interpretation of negative values), Index...
import unittestdef add(x, y):return x + yclass TestAdd(unittest.TestCase):def test_add_positive(self):self.assertEqual(add(1, 2), 3)def test_add_negative(self):self.assertEqual(add(-1, -2), -3)def test_add_zero(self):self.assertEqual(add(0, 0), 0)if __name__ == '__...
print(fruits[0]) #index 0 is the first element print(fruits[1])print(fruits[2])Output:Apple Banana Orange 但是，索引不必总是为正。如果想逆向访问列表，也就是按照相反的顺序，可以使用负索引，如下所示：#Access elements in the fruits list using negative indexesfruits = ['Apple','Banana', "...
negative_float = -2.718 zero_float = 0.0 运算规则: 浮点型数据支持所有的基本数学运算,包括加法、减法、乘法、除法和取模。 # 加法 float_addition = 1.5 + 2.5 # 减法 float_subtraction = 4.0 - 1.0 # 乘法 float_multiplication = 2.0 * 3.0 ...
6.IndexError: list index out of range 越界访问列表,下标超出了列表的范围。 a = [10, 20, 30] print(a[3]) # 由于下标是从0开始计数,此处最大下标为2,修改成a[2] 7.KeyError: 'xxx' 试图访问字典中不存在的键值。 d = {"name": "Tom", "age": 18} ...
index=dataset_train.index) # Random shuffle training data X_train.sample(frac=1) X_test = pd.DataFrame(scaler.transform(dataset_test), columns=dataset_test.columns, index=dataset_test.index) tf.random.set_seed(10) act_func ='relu'