Print in one line dynamically

user_375373 0
Viewed 673111

I would like to make several statements that give standard output without seeing newlines in between statements.

Specifically, suppose I have:

for item in range(1,100):
    print item

The result is:

1
2
3
4
.
.
.

How get this to instead look like:

1 2 3 4 5 ...

Even better, is it possible to print the single number over the last number, so only one number is on the screen at a time?

printing python
22 Answers

So many complicated answers. If you have python 3, simply put \r at the start of the print, and add end='', flush=True to it:

import time

for i in range(10):
    print(f'\r{i} foo bar', end='', flush=True)
    time.sleep(0.5)

This will write 0 foo bar, then 1 foo bar etc, in-place.

user_2127310

Or even simpler:

import time
a = 0
while True:
    print (a, end="\r")
    a += 1
    time.sleep(0.1)

end="\r" will overwrite from the beginning [0:] of the first print.

user_134498660

For those struggling as I did, I came up with the following that appears to work in both python 3.7.4 and 3.5.2.

I expanded the range from 100 to 1,000,000 because it runs very fast and you may not see the output. This is because one side effect of setting end='\r' is that the final loop iteration clears all of the output. A longer number was needed to demonstrate that it works. This result may not be desirable in all cases, but was fine in mine, and OP didn't specify one way or another. You could potentially circumvent this with an if statement that evaluates the length of the array being iterated over, etc. The key to get it working in my case was to couple the brackets "{}" with .format(). Otherwise, it didn't work.

Below should work as-is:

#!/usr/bin/env python3

for item in range(1,1000000):
    print("{}".format(item), end='\r', flush=True)
user_1896250

Note: I point out this solution, because most of the others I've seen don't work if the length of the next print is smaller than the previous one.

If you know what you want to delete, and can afford a global variable, you can simply overwrite the last line with blank spaces.

  1. Before printing, store the length of your string as ‘n’.
  2. Print it, but end with ‘\r’ (it returns to the beginning of the line).
  3. Next time, before printing you message, print ’n’ blank spaces over the line.
_last_print_len = 0
def reprint(msg, finish=False):
    global _last_print_len
    
    # Ovewrites line with spaces.
    print(' '*_last_print_len, end='\r')
    
    if finish:
        end = '\n'
        # If we're finishing the line, we won't need to overwrite it in the next print.
        _last_print_len = 0
    else:
        end = '\r'
        # Store len for the next print.
        _last_print_len = len(msg)
    
    # Printing message.
    print(msg, end=end)

Examples:

for i in range(10):
    reprint('Loading.')
    time.sleep(1)
    reprint('Loading..')
    time.sleep(1)
    reprint('Loading...')
    time.sleep(1)

enter image description here

for i in range(10):
    reprint('Loading.')
    time.sleep(1)
    reprint('Loading..')
    time.sleep(1)
    reprint('Loading...', finish=True)
    time.sleep(1)

enter image description here

user_146561980 
for item in range(1,100):
    if item==99:
        print(item,end='')
    else:
        print (item,end=',')

Output: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99

user_32058220

If you want it as a string, you can use

number_string = ""
for i in range(1, 100):
  number_string += str(i)
print(number_string)
user_78819600
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