Question

What is wrong with my IF ELSE statement?

IF NOT condition, do A.
ELSE, do B.

But the result turns out quite different than I expected. :S

data['stock'] = ['0.02', '0.03', '0.04', '0.00', '0.05', '0.04', '0.05']

x = 0
y = len(data['Keywords'])

while x <= y - 1:
    if data['stock'][x] != 0:
        print data["stock"][x]
        a = a + 1
    else:
        print "hello"
        a = a + 1

Output:
0.02
0.03
0.04
0.00
0.05
0.04
0.05

Answer 1

One obvious problem is that your list contains strings and your code expects numbers. In Python, you are allowed to compare 0 to "0" (they compare unequal).

One way to fix it:

data['stock'] = [0.02, 0.03, 0.04, 0.00, 0.05, 0.04, 0.05]

Also, that loop looks decidedly un-Pythonic. The first step would be to rephrase it like so:

for x in range(len(data['Keywords'])):
    if data['stock'][x] != 0:
        print data["stock"][x]
    else:
        print "hello"

If you don’t use the value of x other than for indexing into the list, then the counter is unnecessary:

for val in data["stock"]:
    if val != 0:
        print val
    else:
        print "hello"

Note that this assumes that data["Keywords"] has the same length and data["stock"]. If that’s not the case, this code isn’t equivalent to yours.