Python if-else code style for reduced code for rounding floats

manpreet Best Answer 2 years ago

Is there any shorter, more legible code style to solve this problem? I am trying to classify some float values into interregional folders.

def classify(value):   
    if value < -0.85 and value >= -0.95:
        ts_folder = r'\-0.9'
    elif value < -0.75 and value >= -0.85:
        ts_folder = r'\-0.8'
    elif value < -0.65 and value >= -0.75:
        ts_folder = r'\-0.7'    
    elif value < -0.55 and value >= -0.65:
        ts_folder = r'\-0.6'   
    elif value < -0.45 and value >= -0.55:
        ts_folder = r'\-0.5'  
    elif value < -0.35 and value >= -0.45:
        ts_folder = r'\-0.4'
    elif value < -0.25 and value >= -0.35:
        ts_folder = r'\-0.3'
    elif value < -0.15 and value >= -0.25:
        ts_folder = r'\-0.2'
    elif value < -0.05 and value >= -0.15:
        ts_folder = r'\-0.1'
    elif value < 0.05 and value >= -0.05:
        ts_folder = r'\0.0'
    elif value < 0.15 and value >= 0.05:
        ts_folder = r'\0.1'
    elif value < 0.25 and value >= 0.15:
        ts_folder = r'\0.2'
    elif value < 0.35 and value >= 0.25:
        ts_folder = r'\0.3'
    elif value < 0.45 and value >= 0.35:
        ts_folder = r'\0.4'
    elif value < 0.55 and value >= 0.45:
        ts_folder = r'\0.5'
    elif value < 0.65 and value >= 0.55:
        ts_folder = r'\0.6'
    elif value < 0.75 and value >= 0.65:
        ts_folder = r'\0.7'  
    elif value < 0.85 and value >= 0.75:
        ts_folder = r'\0.8'
    elif value < 0.95 and value >= 0.85:
        ts_folder = r'\0.9'

    return ts_folder

manpreet 2 years ago

One of the first rules with a block of code like this, is to always make the comparisons be in the same direction. So instead of

    elif value < -0.75 and value >= -0.85:

write

    elif -0.85 <= value and value < -0.75:

At this point you can observe that python allows chaining of comparisons, so you can write:

    elif -0.85 <= value < -0.75:

Which is an improvement itself. Alternatively, you can observe this is an ordered list of comparisons, so if you add in an initial comparisons, you can just write

if value < -0.95:        ts_folder = ''
    elif value < -0.85:      ts_folder = r'\-0.9'
    elif value < -0.75:      ts_folder = r'\-0.8'
    elif value < -0.65:      ts_folder = r'\-0.7'    
    elif value < -0.55:      ts_folder = r'\-0.6'   
    elif value < -0.45:      ts_folder = r'\-0.5'  
    elif value < -0.35:      ts_folder = r'\-0.4'
    elif value < -0.25:      ts_folder = r'\-0.3'
    elif value < -0.15:      ts_folder = r'\-0.2'
    elif value < -0.05:      ts_folder = r'\-0.1'
    elif value < 0.05:       ts_folder = r'\0.0'
    elif value < 0.15:       ts_folder = r'\0.1'
    elif value < 0.25:       ts_folder = r'\0.2'
    elif value < 0.35:       ts_folder = r'\0.3'
    elif value < 0.45:       ts_folder = r'\0.4'
    elif value < 0.55:       ts_folder = r'\0.5'
    elif value < 0.65:       ts_folder = r'\0.6'
    elif value < 0.75:       ts_folder = r'\0.7'  
    elif value < 0.85:       ts_folder = r'\0.8'
    elif value < 0.95:       ts_folder = r'\0.9'
    else:                    ts_folder = ''

That's still quite long, but a) it's a lot more readable; b) it has explicit code to handle value < -0.95 or 0.95 <= value

manpreet 2 years ago

You can use the round() built-in :

ts_folder = "\\" + str(round(value + 1e-16, 1)) # To round ref="https://forum.tuteehub.com/tag/values">values like .05 to .1, not .0
if ts_folder == r"\-0.0": ts_folder = r"\0.0" 

manpreet 2 years ago

round2 = lambda x, y=None: round(x+1e-15, y)
ts_folder = r'\{}'.format(str(round2(value, 1)))

>>> round2(.85, 1)
0.9
>>> round2(-.85, 1)
-0.8