How to compare strings before starting a loop in python

Question

Hi I am pulling a variable, call it x, from urllib.request.urlopen

I then want to make a float comparison.

However, as this variable can vary, and be unavailable, it is occasionally "N/A"

this is my comparison

    x = (sourceCode.split)('sourcesnippet1')[1].split('sourcesnippet2')[0]
    if 0 < float(x) < 1:
        print (entity, 'meets requirements')
        print (x)

how can I make it so that pseudo:

chek = 'N/A'
            x = (sourceCode.split)('sourcesnippet1')[1].split('sourcesnippet2')[0]
if str(x) == chek TRUE, then go to next query
else
            if 0 < float(x) < 1:
                print (entity, 'meets requirements')
                print (x)

m.wasowski · Accepted Answer · 2014-11-30 22:24:49Z

2

Don't use if at all, just try convert it to float, and catch exception:

parts = (sourceCode.split)('sourcesnippet1')
txt = parts[1].split('sourcesnippet2')[0]
try:
    x = float(txt)
except ValueError as err:
    print(err)
    continue
print ("Now I know, that I have a valid float...")
# do your stuff

This is prevalent style in Python, see https://docs.python.org/2/glossary.html#term-eafp

You can also guard against other errors, like .split() returning just one element:

parts = (sourceCode.split)('sourcesnippet1')
try:
    txt = parts[1].split('sourcesnippet2')[0]
    x = float(txt)
except (ValueError, LookupError) as err:
    print(err)
    continue

answered Nov 30, 2014 at 22:24

m.wasowski

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