w3resource

NumPy: Reverse an array

NumPy: Array Object Exercise-6 with Solution

Write a NumPy program to reverse an array (first element becomes last).

Python NumPy: Reverse an array

Sample Solution:-

Python Code:

import numpy as np
import numpy as np
x = np.arange(12, 38)
print("Original array:")
print(x)
print("Reverse array:")
x = x[::-1]
print(x)

Sample Output:

Original array:                                                         
[12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
 36                                                                     
 37]                                                                    
Reverse array:                                                          
[37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14
 13                                                                     
 12] 

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Write a NumPy program to create a array with values ranging from 12 to 38.
Next: Write a NumPy program to an array converted to a float type.

What is the difficulty level of this exercise?

Test your Python skills with w3resource's quiz



Python: Tips of the Day

Python: Kwargs

**kwargs and *args are function arguments that can be very useful.

They are quite underused and often under-understood as well.

Let's try to explain what kwargs are and how to use them.

  • While *args are used to pass arguments at an unknown amount to functions, **kwargs are used to do the same but with named arguments.
  • So, if *args is a list being passed as an argument, you can think of **kwargs as a dictionary that's being passed as an argument to a function.
  • You can use arguments as you wish as long as you follow the correct order which is: arg1, arg2, *args, **kwargs. It's okay to use only one of those but you can't mix the order, for instance, you can't have: function(**kwargs, arg1), that'd be a major faux pas in Python.
  • Another example: You can do function(*args,**kwargs) since it follows the correct order.
  • Here is an example. Let's say satelites are given with their names and weight in tons in dictionary format. Code prints their weight as kilograms along with their names.
def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)
payloads(NavSat1 = '2.5', BaysatG2 = '4')

Output:

NavSat1 ||| 250.0
BaysatG2 ||| 400.0

Since the function above would work for any number of dictionary keys, **kwargs makes perfect sense rather than passing arguments with a fixed amount.

def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)

sats={"Tx211":"3", "V1":"0.50"}
payloads(**sats)

Output:

Tx211 ||| 300.0
V1 ||| 50.0