枚举用于在Python中查找元素的列表

Question

In python how to iterate over list of elements and find if my required elements are present in the list or not.

Then print if any one of those are found in the list, else say no elements found. (& Assert my code at the end )

I want to search and find for only mandatory 3 elements which are 'Name', 'Year' and 'City_id' from a list.

And finally assert with foundcount so that test fails or passes.

Here is my code:

list = [ 'Name, 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time']

reqVal = [ 'Name', 'Year', 'City_id' ] # items in List - if present or not
foundCount = 0

def isValInList():
    for reqVal in enumerate(list):
        if reqVal in list :
            print("Yes, %s required item is found in List : ", reqVal)
            foundCount += 1
        else:
            print('No required items are found in list')
            break


        assert (foundCount == 0)

isValInList()

So currently when I run this code, I get

No required items are found in list

Which is obviously wrong, can you please suggest and correct where I am doing it wrong. thanks.

Answer 1

you could try:

my_list = ['Name', 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time']
reqVal = ['Name', 'Year', 'City_id']

count_for_reqVal = {req_val : my_list.count(req_val) for req_val in reqVal}

print(count_for_reqVal)

#output : {'Name': 1, 'Year': 1, 'City_id': 1}

also, I was trying to reuse your code:

list = [ 'Name', 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time']

reqVal = [ 'Name', 'Year', 'City_id', 'Test' ] # items in List - if present or not


def isValInList():
    foundCount = 0

    for val in reqVal:
        if val in list :
            print("Yes, '%s' required item is found in list" %  val)
            foundCount += 1

        else:
            print("No, '%s' required item is not in list" %  val)

    if foundCount == 0:
            print('No required items are found in list')



isValInList()

# output:
# Yes, 'Name' required item is found in list
# Yes, 'Year' required item is found in list
# Yes, 'City_id' required item is found in list
# No, 'Test' required item is not in list

Answer 2

Quite a lot going on: - Don't use predefined names like list as variable names - You need to pass your variables to the function - What is your assert good for? - foundCount must be declared as global - enumerate generates a tuple - What is the break good for?

This works:

alist = ['Name', 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time']

reqVal = ['Name', 'Year', 'City_id' ] # items in List - if present or not

def isValInList(alist, blist):
    global foundCount
    for num, entry_a in enumerate(alist):
        if entry_a in blist :
            print("Yes, %s required item is found in List : ", entry_a)
            foundCount += 1
        else:
            print('No required items are found in list')

isValInList(alist, reqVal)

Answer 3

Using Set +info

list = { 'Name', 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time'}

reqVal = { 'Name', 'Year', 'City_id' } # items in List - if present or not

def isValInList():
    assert True, reqVal.issubset(list)

isValInList()

Answer 4

Your question is not quite understandable.Be more specific.I wrote the answer as I understood your question. list = [ 'Name, 'Year', 'City_id', 'Region_Id' , 'Location', 'Source', 'Time']

reqVal = [ 'Name', 'Year', 'City_id' ] # items in List - if present or not
foundCount = 0

if 'Name' in list and 'Year' in list 'City_id' in list:
    print('All are present')

Answer 5

If we want to convert the list into an iterable list of tuples (or get the index based on a condition check, for example in linear search you might need to save the index of minimum element), you can use the enumerate() function.

Example:

# Python3 code to iterate over a list 
list = [1, 3, 5, 7, 9] 

# Using enumerate() 
for i, val in enumerate(list): 
    print (i, ",",val) 

Note : Even method #2 can be used to find the index, but method #1 can't (Unless an extra variable is incremented every iteration) and method #5 gives a concise representation of this indexing.

Answer 6

You are iterating over the wrong list:

for reqVal in enumerate(list):
    if reqVal in list :

try:

for item in reqVal:
    if item in list:
        print("Yes, %s required item is found in List : ", element)
        foundCount += 1

    else:
        print('No required items are found in list')

This way there is no need for enumerate. I don't see the point of breaking the loop before iterating over all the items.

Furthermore, It is better not to use "list" as a var name for this is a key word in python.