Type/dtype/astype usage in Python

There are three functions and attributes related to data types in Python: type/dtype/astype.

name	describe
type()	Returns the data type of the parameter
dtype	Returns the data type of the elements in the array
astype()	Convert data types

1.type() is used to get the data type

#type用于获取数据类型
import numpy as np
a=[1,2,3]
print(type(a))
#>>><class 'list'>
b=np.array(a)
print(type(b))
#>>><class 'numpy.ndarray'>

2.dtype() is used to get the type of elements in the array

#dtype用于获取数组中元素的类型
print(b.dtype)
#>>>int64

x,y,z=1,2,3
c=np.array([x,y,z])
print(c.dtype)
#>>>int64

d=np.array([1+2j,2+3j,3+4j])
print(d.dtype)
#>>>complex128

3.astype() to modify the data type

#astype修改数据类型
e=np.linspace(1,5,20)
print(e)
#>>>
'''
[1.         1.21052632 1.42105263 1.63157895 1.84210526 2.05263158
 2.26315789 2.47368421 2.68421053 2.89473684 3.10526316 3.31578947
 3.52631579 3.73684211 3.94736842 4.15789474 4.36842105 4.57894737
 4.78947368 5.        ]
'''
print(e.dtype)
#>>>float64

e=e.astype(int)
print(e)
#>>>[1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 5]
print(e.dtype)
#>>>int64

Usage in Dataframe: convert the type of data in the specified field

import pandas as pd
e=np.linspace(1,5,20)
edf=pd.DataFrame(e)
edf[0].head(3)
#>>>
0    1.000000
1    1.210526
2    1.421053
Name: 0, dtype: float64

print(edf[0].dtype)
#>>>float64

edf[0]=edf[0].astype(int)
edf[0].head(3)
#>>>
0    1
1    1
2    1
Name: 0, dtype: int64

print(edf[0].dtype)
#>>>int64