'Waiting' animation in command prompt (Python)

I have a Python script which takes a long tim开发者_运维问答e to run. I'd quite like to have the command line output to have a little 'waiting' animation, much like the swirly circle we get in browsers for AJAX requests. Something like an output of a '\', then this is replaced by a '|', then '/', then '-', '|', etc, like the text is going round in circles. I am not sure how to replace the previous printed text in Python.

Use \r and print-without-newline (that is, suffix with a comma):

animation = "|/-\\"
idx = 0
while thing_not_complete():
    print(animation[idx % len(animation)], end="\r")
    idx += 1
    time.sleep(0.1)

For Python 2, use this print syntax:

print animation[idx % len(animation)] + "\r",

Just another pretty variant

import time

bar = [
    " [=     ]",
    " [ =    ]",
    " [  =   ]",
    " [   =  ]",
    " [    = ]",
    " [     =]",
    " [    = ]",
    " [   =  ]",
    " [  =   ]",
    " [ =    ]",
]
i = 0

while True:
    print(bar[i % len(bar)], end="\r")
    time.sleep(.2)
    i += 1

A loading bar useful for if you're installing something.

animation = [
"[        ]",
"[=       ]",
"[===     ]",
"[====    ]",
"[=====   ]",
"[======  ]",
"[======= ]",
"[========]",
"[ =======]",
"[  ======]",
"[   =====]",
"[    ====]",
"[     ===]",
"[      ==]",
"[       =]",
"[        ]",
"[        ]"
]

notcomplete = True

i = 0

while notcomplete:
    print(animation[i % len(animation)], end='\r')
    time.sleep(.1)
    i += 1

if you want to make it last a couple seconds do

if i == 17*10:
    break

after the

i += 1

I think for best practices you can put a if condition at the end of the loop to avoid overflow with 'idx' variable in the case where the waiting funtion last longer than expexted:

import time

animation_sequence = "|/-\\"
idx = 0
while True:
    print(animation_sequence[idx % len(animation_sequence)], end="\r")
    idx += 1
    time.sleep(0.1)

    if idx == len(animation_sequence):
        idx = 0

    # Verify the change in idx variable
    print(f'   idx: {idx}', end='\r')

Python's built-in curses package contains utilities for controlling what is printed to a terminal screen.