String match with 'in'

August 3, 2022

In the following code, I would like to search a match for elements in a list in a given string.

lst1 = ['LOP3', 'FOO']
lst2 = ['PLOP3', 'BAR']

x = 'LOP3.LUT'
y = 'PLOP3.LUT'

for i1 in lst1:
    if i1 in x:
        print('yes1')
    if i1 in y:
        print('yes2')

for i2 in lst2:
    if i2 in x:
        print('yes3')
    if i2 in y:
        print('yes4')

When I run the code, I see

yes1
yes2
yes4

That means lst1[0] is found in y which results in yes2. That is wrong in my case. x doesn’t start with PLOP3 although it has LOP3 in its name. So, I would like to see yes1, yes4 only. How can I fix that code?

>Solution :

"That means LOP3 is found in lst1[0] which results in yes2."

No, lst1[0], 'LOP3', is found in y, 'PLOP3.LUT'. Other way around. That causes it to print yes2. So perhaps you want to reverse that expression, a in b to b in a?

Or perhaps you want the startswith method, e.g. if x.startswith(i1):?