Numpy 简明教程
NumPy - Array Creation Routines
可以通过以下任何数组创建例程或使用低级 ndarray 构造函数构建一个新的 ndarray 对象。
A new ndarray object can be constructed by any of the following array creation routines or using a low-level ndarray constructor.
numpy.empty
它创建一个指定形状和数据类型的未初始化数组。它使用以下构造函数 −
It creates an uninitialized array of specified shape and dtype. It uses the following constructor −
numpy.empty(shape, dtype = float, order = 'C')
构造函数需要以下参数。
The constructor takes the following parameters.
Sr.No. |
Parameter & Description |
1 |
Shape Shape of an empty array in int or tuple of int |
2 |
Dtype Desired output data type. Optional |
3 |
Order 'C' for C-style row-major array, 'F' for FORTRAN style column-major array |
Example
以下代码显示了一个空数组的示例。
The following code shows an example of an empty array.
import numpy as np
x = np.empty([3,2], dtype = int)
print x
输出如下 −
The output is as follows −
[[22649312 1701344351]
[1818321759 1885959276]
[16779776 156368896]]
Note − 由于数组中的元素未初始化,所以它们显示随机值。
Note − The elements in an array show random values as they are not initialized.
numpy.zeros
返回一个指定的尺寸的新数组,并用零填充。
Returns a new array of specified size, filled with zeros.
numpy.zeros(shape, dtype = float, order = 'C')
构造函数需要以下参数。
The constructor takes the following parameters.
Sr.No. |
Parameter & Description |
1 |
Shape Shape of an empty array in int or sequence of int |
2 |
Dtype Desired output data type. Optional |
3 |
Order 'C' for C-style row-major array, 'F' for FORTRAN style column-major array |
Example 1
# array of five zeros. Default dtype is float
import numpy as np
x = np.zeros(5)
print x
输出如下 −
The output is as follows −
[ 0. 0. 0. 0. 0.]
numpy.ones
返回指定尺寸和类型的新数组,并用 1 填充。
Returns a new array of specified size and type, filled with ones.
numpy.ones(shape, dtype = None, order = 'C')
构造函数需要以下参数。
The constructor takes the following parameters.
Sr.No. |
Parameter & Description |
1 |
Shape Shape of an empty array in int or tuple of int |
2 |
Dtype Desired output data type. Optional |
3 |
Order 'C' for C-style row-major array, 'F' for FORTRAN style column-major array |