You can assign a conditional expression to a variable. If the expression is true, its value is 1. Otherwise, it is 0. For example:

patientid = 42113
condvalue = patientid == 42113
# condvalue is now 1

Conversely, you can use almost any expression as a conditional expression. If its value is non-zero, it is evaluated as true. Otherwise, it is false. For instance:

patientid = 42113
if patientid:
    print "patientid is non-zero, and the condition is true"

	An expression containing an assignment cannot be used as a conditional expression: if patientid = 42113: # this generates an error This is to keep you from specifying patientid = 42113 when you really meant to specify patientid == 42113. Many programming languages allow you to do this, and it can be difficult to spot this error.

The special values True and False can be used in conditional expressions. True is handy to use if you want to create a loop in which the test condition is in the middle.

For example, here is a loop that displays the numbers from 1 to 10 but skips 5:

x = 0
while True:
    x = x + 1
    if x == 5:
        continue
    print x
    if x == 10:
        break