前言

numpy是Python的一种开源的数值计算扩展工具，这种工具可用来存储和处理大型矩阵

使用

安装

pip install numpy

基准示例

• list(列表)转换成array(数组)

>>> import numpy as np
>>> getAllData = [['retailer', 'price', 'weight', 'totalValue'], ['liyi', 100.0, 100.0, 10000.0], ['daier', 99.0, 99.0, 9801.0], ['shangsan', 98.0, 98.0, 9604.0], ['qinsi', 97.0, 97.0, 9409.0], ['tangwu', 96.0, 96.0, 9216.0]]
>>> data = np.asarray(getAllData)
>>> data
array([['retailer', 'price', 'weight', 'totalValue'],
       ['liyi', '100.0', '100.0', '10000.0'],
       ['daier', '99.0', '99.0', '9801.0'],
       ['shangsan', '98.0', '98.0', '9604.0'],
       ['qinsi', '97.0', '97.0', '9409.0'],
       ['tangwu', '96.0', '96.0', '9216.0']], dtype='<U10')
>>> type(data)
<class 'numpy.ndarray'>

获取列表中第一行的值

>>> data[1, :]
array(['liyi', '100.0', '100.0', '10000.0'], dtype='<U10')

获取数组中第一列的值

>>> data[:, 0]
array(['retailer', 'liyi', 'daier', 'shangsan', 'qinsi', 'tangwu'],
      dtype='<U10')

结语

详参Numpy