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Python

Posted by Colin Hartmann
Colin Hartmann
Courses Plus Student 2,875 Points

NEED HELP TO SEARCH FOR STRING VALUE IN DICTIONARY

I have dictionaries filled with keys of keys. I am trying to create a function to be able to search for if the key has "sg" or "pl".

Here are two examples of two such dictionaries:

Types of conjugations

persons = {1: "1st person sg", 2: "2nd person sg", 3: "3rd person sg", 4: "1st person pl", 5: "2nd person pl", 6: "3rd person pl"};

Future Tense

futureTenseEndings = {persons[1]: "é", persons[2]: "ás", persons[3]: "á", persons[4]: "ámos", persons[5]: "áis", persons[6]: "án"};

Here is some code I found online:

#Just an example how the dictionary may look like
myDict = {'age': ['12'], 'address': ['34 Main Street, 212 First Avenue'],
      'firstName': ['Alan', 'Mary-Ann'], 'lastName': ['Stone', 'Lee']}

def search(values, searchFor):
    for k in values:
        for v in values[k]:
            if searchFor in v:
                return k
    return None

#Checking if string 'Mary' exists in dictionary value
print(search(myDict, 'Lee')); #prints firstName

Now, for the function search(), I do NOT understand exactly how it's working. Could someone please explain it to me???

2 Answers

Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

Hi Colin

see below 

#Just an example how the dictionary may look like
myDict = {'age': ['12'], 'address': ['34 Main Street, 212 First Avenue'],
      'firstName': ['Alan', 'Mary-Ann'], 'lastName': ['Stone', 'Lee']}

def search(values, searchFor):
    for k in values: # lopping through every key in the dictionary 
        for v in values[k]: # chekcing the value for each key
            if searchFor in v: # if the value matches your searchFor then return that key
                return k
    return None # not sure what this line is meant to be doing 

#Checking if string 'Mary' exists in dictionary value
print(search(myDict, 'Lee')); #prints firstName


# see my code . if i want to find the address for Mary as an example 

myDict = {'age': ['12'], 'address': ['34 Main Street, 212 First Avenue'], 'firstName': ['Alan', 'Mary-Ann'], 'lastName': ['Stone', 'Lee']}

def search(values, searchFor):
  for key,value in values.items(): # getting each key and val for the dic
    for val in value: # the values are all lists which i can loop around
      if searchFor in val: # if the search term in the list 
        print("{}".format(values['address'])) # print out the value where the key is the address



search(myDict,"Mary")  # returns ['34 Main Street, 212 First Avenue']
Colin Hartmann
Colin Hartmann
Courses Plus Student 2,875 Points

please explain the syntax of the following line: for key,value in values.items(): # getting each key and val for the dic

Why is there a comma (','), between "key" and "value"? What does the "in" statement do?

Sorry but I'm new to python.

Also, just to note, this is a personal project and I haven't actually taken any courses on Python in Treehouse

Andreas cormack
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points
Andreas cormack
.a{fill-rule:evenodd;}techdegree seal-36
Andreas cormack
Python Web Development Techdegree Graduate 33,011 Points

Hi Colin

dictionary.items() method return a key, value pair which is a tuple. Follow this link for an explanation of tuples http://www.tutorialspoint.com/python/python_tuples.htm.

Say i had a tuple like so (40,50), i could assign these value to variables like so tmp1, tmp2 = (40,50) which assigns the value 40 to tmp1 and 50 to tmp2. In the same way i am saying for key,value in values.items() which return a tuple of the keys and values for that dictionary. The 'in' operator does what says, it looks for something in something.So seeing as the values are all lists i can say, is the search word in the list i.e each val which is a list.

Hope this helps a bit

If your new to python, take the python basics course it will make you life a lot easier.