numpy1

中文版：NumPy 复习 1

some examples for Numpy 1

1. always import the package first!

import numpy

import numpy as np

2. create variables (array) which can be used in Numpy.

# create from list 1
l=[1,2,3]
a=np.array(l)
print("l=",l,type(l))
print("a=",a,type(a))

# create from list 2
b=np.array([1,2,3])
print("b=",b,type(b))

# create from list 3
c=np.array([[1,2,3]])
print("c=",c,type(c)) #what is the difference between b and c? 1D array or 2D array

# create from list 4
d=np.array([[1,2,3],[4,5,6]])
print(d)

# create from list 5
e=np.array([[[1,2,3],[4,5,6]],[[1,2,3],[4,5,6]],[[1,2,3],[4,5,6]]])
print(e) # what is the dimension of e?

practice 1

1. create two arrays:

$$A=\left[\begin{array}{ccc}1& 2& 3\end{array}\right]$$

and

$$B=\left[\begin{array}{cc}1& 2\\ 4& 5\end{array}\right]$$

fix the errors:

import(numpy)

import Numpy

import Numpy NP

import numpy as np
l=NP.array([1])
print(l)

l=numpy.aray([2,2])

l=ny. array([[1],[1]])

l=ny.array([[1,2,3],[4,5,6])