CODEWITHSUNDEEP
pythonpython-3.xlistsearch
express_v2
express_v2

Reputation: 131

Python - Searching multiple values in list and performing multiple operations

I'm trying to search a list I have for specific values and if any of those values exist in the list, I would like to perform a different operation.

Currently this is the list I am working with:

print(categories)
['Creams', 'Bath', 'Personal Care']

What I would like to do is search this categories list for some different values. To do this, I've converted categories into a set and am individually searching for each of the values with an if statement.

For example:

c = set(categories)
if "Conditioners" in c:
     print("1")
if "Bath" in c: 
     print("2")
if "Shaving Gels" in c:
     print("3")

Which returns:

2

What I would ideally like to do is put my criteria into a list or some other relevant data structure and have it perform that particular operation if that value exists within categories in an efficient manner.

Upvotes: 4

Views: 6221

Answers (6)

scharette
scharette

Reputation: 9977

I'd like to suggest another neat and maintainable alternative to dictionaries. You could also create a class with @staticmethod and use getattr to call methods like so, 

categories = ['Creams', 'Bath', 'Personal Care']

class CategoriesWorker:
    @staticmethod
    def Creams():
        print(1)
    @staticmethod
    def Bath():
        print(2)
    @staticmethod
    def PersonalCare():
        print(3)

for category in categories:
    try:
        getattr(CategoriesWorker, category.replace(" ", ""))()
    except AttributeError:
        pass

>>>
1
2
3

Note here that naming of your @staticmethods is crucial. I basically use a the same value without spaces and then strip them of the actual value in the list to retrieve it in the class.

Basically, I suggested this in order to overcome the problem where using a dictionary in conjunction with lambdas could lead to unreadable code. Indeed, your specific example ask to simply print() values. But what if the logic of the methods was more complicated ? You'd be writing a unreadable dictionary fast enough.

Now, an alternative you be to wrap the logic in a method and use it in a dictionary. 

categories = ['Creams', 'Bath', 'Personal Care','test']
def Creams():
  print(1)

def Bath():
  print(2)

def PersonalCare():
  print(3)

comparison_dict = {'Creams':Creams,'Bath':Bath,'Personal Care':PersonalCare}


for category in categories:
  comparison_dict.get(category, lambda: None)()

>>>>
1
2
2

That would be valid also. I just like the class definition better since it is clear what this class intends to do and I like to have related code at one compact emplacement.

Upvotes: 1

Luke Polson
Luke Polson

Reputation: 444

Probably a dictionary would be a suitable datatype. You could complete your task like such.

diction = {"Conditioners": 1, "Bath": 2} #add whatever else you want

for item in categories:
        try:
           print(diction[item])
        except:
            continue

Upvotes: 1

W Stokvis
W Stokvis

Reputation: 1439

IIUC, this is what you're looking for. dict comprehension with enumerate. This will also reduce the amount of manual labor required so long as your list is in the order you want.

d = {k:v for v,k in enumerate(categories,1)}
d
{'Creams': 1, 'Bath': 2, 'Personal Care': 3}

You can perform whatever operation you want on the dictionary.

c = ['Conditioners','Bath','Shaving Gels']
for i in c:
    print (d.get(i, None))
None
2
None

Upvotes: 2

whackamadoodle3000
whackamadoodle3000

Reputation: 6748

Something like this (for the exact case you put above)

a=['Creams', 'Bath', 'Personal Care']
b=['Conditioners','Bath','Shaving Gels']
[print(c-1) for c,e in b if e in enumerate(a)]

Upvotes: 0

Hearner
Hearner

Reputation: 2729

categories = ['Creams', 'Bath', 'Personal Care']
criteria = {"Conditioners" : "1", "Bath" : "2", "Shaving Gels" : "3"}

# loop through all the categories
for i in set(categories):
    # if the category is in the criteria print the value
    if i in criteria.keys():
        print(criteria[i]) #print 2

Upvotes: 0

Andrej Kesely
Andrej Kesely

Reputation: 195438

You can store your functions in dictionary, where values are desired functions. That way, you have easy access to them by keys and you can traverse categories normally:

categories = ['Creams', 'Bath', 'Personal Care']

my_dict = {
    'Conditioners': lambda: print(1),
    'Bath': lambda: print(2),
    'Shaving Gels': lambda: print(3)
}


for category in categories:
    fn = my_dict.get(category, lambda: None)
    fn()

Output:

2

Upvotes: 6

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