CODEWITHSUNDEEP
pythonprintingprogress-bar
Gianni Spear
Gianni Spear

Reputation: 7924

print a progress-bar processing in Python

I wrote this simple function "processing_flush" in order to print a sequence of points (given by index) to test if my software is processing my data and eventually the speed. The total size of my data is unknown.

    import sys
    import time

    def processing_flush(n, index=5):
        sys.stdout.write("\rProcessing %s" % ((n % index)* "."))
        sys.stdout.flush()

    for n in xrange(20):
        processing_flush(n, index=5)
        time.sleep(1)

The problem that i cannot fix is when all points are printed the first time (ex: Processing .... if index is equal to 5) the cursor doesn't start from zero.

Upvotes: 4

Views: 2482

Answers (1)

Johannes Overmann
Johannes Overmann

Reputation: 5151

Before you overwrite the same line again you need to clear at least the positions where the dots are with spaces.

def processing_flush(n, index=5):
    sys.stdout.write("\rProcessing %s" % (index * " "))
    sys.stdout.write("\rProcessing %s" % ((n % index)* "."))
    sys.stdout.flush()

The code above may lead to some brief flicker. In your specific case it is sufficient to clear the line when n % index becomes 0:

def processing_flush(n, index=5):
    if n % index == 0:
        sys.stdout.write("\rProcessing %s" % (index * " "))
    sys.stdout.write("\rProcessing %s" % ((n % index)* "."))
    sys.stdout.flush()

Or even better always write index-1 characters:

def processing_flush(n, index=5):
    sys.stdout.write("\rProcessing %s%s" % ((n % index)* ".", (index - 1 - (n % index))* " "))
    sys.stdout.flush()

Edit 1: Or if you prefer to have the cursor always after the last dot:

def processing_flush(n, index=5):
    sys.stdout.write("\rProcessing %s%s" % ((n % index)* ".", (index - 1 - (n % index))* " "))
    sys.stdout.write("\rProcessing %s" % ((n % index)* "."))
    sys.stdout.flush()

Edit 2: Or if you prefer to have the cursor always at the beginning of the line:

def processing_flush(n, index=5):
    sys.stdout.write("Processing %s%s\r" % ((n % index)* ".", (index - 1 - (n % index))* " "))
    sys.stdout.flush()

The reason is that your shell remembers the remaining characters of the previous line if you overwrite just the first part of it.

Upvotes: 6

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