Printing a line dynamically in python 3

Question

I'm trying to print a line in python 3 that will change as the program goes on. For example, if I try:

import time
for i in range(0,10):
    print('Loading' + '.'*i)
    time.sleep(0.5)

I get:

Loading.
Loading..
Loading...

and so on. Can I make it that the previous line changes and gets another '.' added to it instead of printing a new one? Of course, I could do:

import time, os
for i in range(0,10):
    os.system('cls')
    print('Loading' + '.'*i)
    time.sleep(0.5)

but that causes problems of its own. I know this question has been asked before, but all the answers given to it for some reason don't work. Doing something like:

import time
for i in range(0,10):
    print('Loading' + '.'*i, end="\r")
    time.sleep(0.5)

doesn't change anything, and replacing "\r" with " " just makes python not print anything for a while and then print out the whole row. What am I doing terribly wrong?

score 2 · Accepted Answer · answered Dec 01 '15 at 02:01

2

import time
print('Loading', end='.')
for i in range(0,10):
    print('', end=".")
    time.sleep(0.5)

see explanation of end syntax and working example.

answered Dec 01 '15 at 02:01

Paul Gowder

2,079
1
17
30

Doing `print('.', end='')` is more intuitive imo, just omitting the newline. – Felk Dec 01 '15 at 02:03
@Felk you're probably right about that. – Paul Gowder Dec 01 '15 at 02:04
That just doesn't print out anything for about 5 seconds, then I get 'Loading...........' in one print... – Vladimir Shevyakov Dec 01 '15 at 02:23
That's really weird. Does the second link in the answer (which goes to a runnable example) work for you? If it does, but it doesn't work in your interpreter, are you absolutely sure you're using python3? (Might also be a system clock or speed issue.) – Paul Gowder Dec 01 '15 at 02:42
The second link won't open: 'Secure connection to server failed.'. Not sure what the problem is there. I noticed that all the answers work for most people, but not for me - maybe some strange python glitch...? BTW I am using python 3.4 – Vladimir Shevyakov Dec 01 '15 at 02:45
On the second link, try the version w/o HTTPS, http://repl.it/B4m4/1 – Paul Gowder Dec 02 '15 at 00:52

score 1 · Answer 2 · answered Dec 01 '15 at 01:59

1

You can use a carriage return \r to rewrite the current line like this:

import time
for i in range(50):
    print("Loading" + "."*i, end="\r")
    time.sleep(0.1)

answered Dec 01 '15 at 01:59

Felk

6,165
1
27
51

I already tried that - gives the same output as the code in the question... – Vladimir Shevyakov Dec 01 '15 at 02:21
what kind of console are you outputting to? – Felk Dec 01 '15 at 03:00
I'm using WinPython, outputing to the standard console. – Vladimir Shevyakov Dec 02 '15 at 00:22

score 0 · Answer 3 · answered Dec 01 '15 at 01:54

0

You could use the ANSI clear screen escape character as

print(chr(27) + "[2J")

answered Dec 01 '15 at 01:54

fcortes

92
2
7

I just get massive amounts of '[2J's – Vladimir Shevyakov Dec 01 '15 at 02:35
It works for me with OSX and python3. Should also work with linux – fcortes Dec 01 '15 at 03:48
I'm using windows 7... – Vladimir Shevyakov Dec 02 '15 at 21:58

Printing a line dynamically in python 3

3 Answers3