numpy の基本

programming python numpy
  • numpy の関数
    • np.arange(bgn, end, step): [bgn, end) 間, step 刻みの値を返す
    • np.linspace(bgn, end, nPt): [bgn, end] 間, nPt個の等間隔な値を返す
    • np.ones(row, col): row行, col列の、各要素が 1 である行列を返す
    • np.eye(n): n行, n列の単位行列を返す
#!/usr/bin/env python
import numpy as np


def work():
    a = np.arange(10)
    b = np.arange(1.0, 2.5, 0.5)
    c = np.linspace(0, 1, 5)
    d = np.linspace(0, 1, 5, endpoint=False)
    
    print a   # array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
    print b   # array([1.0, 1.5, 2.0])
    print c   # array([0.0, 0.25, 0.5, 0.75, 1.0])
    print d   # array([0.0, 0.2, 0.4, 0.6, 0.8])


    e = np.ones((2, 4))
    f = np.ones(5, dtype=np.int)
    g = np.eye(3)
    
    print e
    # array([[1, 1, 1, 1],
    #        [1, 1, 1, 1]])

    print e.dtype    # float64
    
    print f          # array([1, 1, 1, 1, 1])
    
    print f.dtype    # int32

    print g
    # array([[1, 0, 0],
    #        [0, 1, 0],
    #        [0, 0, 1]])

    print g.dtype    # float64


if __name__ == "__main__":
    work()