Python comparing two list of tuple elements

Question

I have to compare two list of tuple elements and combine some math calculation of the elements themselves.

More precisely, I have the following lists, every tuple of the list_1 represents a single character and it's frequence into a text ex. ("a" : "10), every tuple of the list_2 represents a bigram of characters and their frequence into the same text ex. ("a", "b" , "2") :

list_1=[("a","10"), ("b","5"), ("c","3"),("d","1")]
list_2= [("a", "b", "4"), ("b","c","1")]

I need to iterate over the two lists and in the case there is a match between the characters of list_2 and the caracters of the list_1, my goal is to make the following analisys:

x= ("a","10")*("b","5")/("a","b","4")= 10*5/4

I hope i was clear in the explanation of the problem...

well, since you seem to know exactly what you want to do I suggest you write some code? — user3012759
– user3012759, Commented Dec 2, 2016 at 10:41

SparkAndShine · Accepted Answer · 2016-12-02 10:49:25Z

2

Try this,

list_1=[("a","10"), ("b","5"), ("c","3"),("d","1")]
list_2= [("a", "b", "4"), ("b","c","1")]

# Convert list_1 into a dict
d = {t[0]:int(t[1]) for t in list_1}

result = [d.get(t[0], 0)*d.get(t[1], 0)*1.0/int(t[2]) for t in list_2]

print(result)
#[12.5, 15.0]

answered Dec 2, 2016 at 10:49

SparkAndShine

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4 Comments

CosimoCD Over a year ago

Thanks so much sparkandshine! Your answer works good! I have only another little question. What I have to do if I want a result like this: ab=12.5 , bc=15.0 ?

SparkAndShine Over a year ago

Try this, for t, value in zip(list_2, result): print(''.join([t[0], t[1], '=', str(value)]))

CosimoCD Over a year ago

Hello sparkandshine! Now I need to solve the same problem but I have three characters in evry item of the list_2? For ex. list_2[("a", "b", "c", 3)]. How can I change cope with this?

SparkAndShine Over a year ago

@CosimoCuriale, do something like result = [d[t[0]]*d[t[1]]*d[t[2]]/int(t[3]) for t in list_2].

pylang · Accepted Answer · 2016-12-02 16:32:45Z

1

@sparkandshine's is the better solution, but for clarity, here is a verbose approach for those new to Python and unfamiliar with comprehensions:

def compute(bigrams, table):
    """Yield a resultant operation for each bigram."""
    for bigram in bigrams:
        # Get values and convert strings 
        x = int(table[bigram[0]])
        y = int(table[bigram[1]])
        z = int(bigram[2])

        operation = (x * y) / z
        yield operation


list(compute(list_2, dict(list_1)))
# [12.5, 15.0]

answered Dec 2, 2016 at 16:32

pylang

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