CODEWITHSUNDEEP
python
Dave Jones
Dave Jones

Reputation: 31

python check if values exist in list

couldn't get this correct. I want to check the contents of the list for a set of values. I should not be falling inside the conditional if because the value doesn't exist.

Following list contains: ['pm_pmdo', 'pm_pmco', 'shv', 'dsv', 'pmv']

Checking for the following: she, dse, pme

inside found one?

class newfunc(object):

    def testfunction(self):

        self.DSE = 'dse'
        self.PME = 'pme'
        self.SHE = 'she'

        self.users_roles = ['pm_pmdo', 'pm_pmco', 'shv', 'dsv', 'pmv']

        print 'Following list contains:'
        print self.users_roles
        print 'Checking for the following:'
        print self.SHE
        print self.DSE
        print self.PME

        if (self.DSE or self.PME or self.SHE for s in self.users_roles):
        #if (self.DSE or self.PME or self.SHE) in self.users_roles:
            print "inside found one"
        else:
            print "outside none found"

if __name__ == '__main__':
    runtime = newfunc()
    runtime.testfunction()

Upvotes: 1

Views: 1255

Answers (3)

martineau
martineau

Reputation: 123541

sets are good containers for quick membership testing if order doesn't matter:

class NewFunc(object):
    def testfunction(self):
        self.DSE = 'dse'
        self.PME = 'pme'
        self.SHE = 'she'

        self.users_roles = {'pm_pmdo', 'pm_pmco', 'shv', 'dsv', 'pmv'}

        print 'users_roles:'
        print list(self.users_roles)
        print 'Checking for the following:'
        print self.SHE
        print self.DSE
        print self.PME

        if {self.DSE, self.PME, self.SHE} & self.users_roles:
            print "found at least one"
        else:
            print "none found"

if __name__ == '__main__':
    runtime = NewFunc()
    runtime.testfunction()

Upvotes: 1

Padraic Cunningham
Padraic Cunningham

Reputation: 180522

Use any which short circuits returning True if we do find a match or evaluates to False otherwise:

if any(s in self.users_roles for s in (self.DSE , self.PME , self.SHE ))

Your code always evaluates to True as if self.DSE is basically checking if bool(self.DSE) which will always evaluate to True for any non empty string, it is the same for self.PME and self.SHE.

In [21]: bool("foo") # will be the same for all non empty strings
Out[21]: True

In [22]: bool("")
Out[22]: False

You can also make self.users_roles a set and use set.intersection:

self.users_roles = {'pm_pmdo', 'pm_pmco', 'shv', 'dsv', 'pmv'}

if self.users_roles.intersection([self.DSE, self.PME, self.SHE])

Upvotes: 0

kindall
kindall

Reputation: 184395

if any(role in self.users_roles for role in (self.SHE, self.PME, self.SHE)):

Upvotes: 2

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