how to check this or that characters in string in python?

Question

When I used only a string or character to check occurrence in string then it works fine but when I used two strings ("a" or "b" in string) then it doesn't work

lst =["test in a", "test in b" "test b in a", "a test b", "test"]
for i in lst:
 if("a" or "b" in lst):
 print("true")
 else:
 print("false")

expected result:

true
true
true
true
false

• Linh Nguyen: isn't it supposed to be if("a" in i) or ("b" in i) ?
• Tula Magar: yes, but if("a" or "b" in i) is same as if ("a" in i) or ("b" in i) or isn't it?
• Linh Nguyen: no that not how to use or condition in python, you want for it to represent A or B, you basically writing A or (B in i)
• 001: No. Because in has higher precedence than or you have if "a" or ("b" in i). And "a"is always "truthy"

Answer 1

try this,

lst =["test in a", "test in b" "test b in a", "a test b", "test"]
 for i in lst:
 if any(item in i for item in ['a', 'b']):
 print("true")
 else:
 print("false")

Answer 2

You don't even need brackets,

if "a" in i or "b" in i:

Answer 3

You could shrink this to one line using list comprehensions as follows:

lst =["test in a", "test in b" "test b in a", "a test b", "test"]
test = [True if (("a" in i) or ("b" in i)) else False for i in lst]

I personally prefer lambdas for situations like these:

# This is written a bit wide, my style for these sort of things
f = lambda x: True if "a" in x else True if "b" in x else False
test = [f(i) for i in lst]

Answer 4

Firstly, you're missing a comma , in your list. Once fixed that, try this:

>>> lst =["test in a", "test in b", "test b in a", "a test b", "test"]
>>> test_set = {'a', 'b'}
>>> for text in lst :
... print len(test_set & set(text)) > 0
... 
True
True
True
True
False