Sometimes, while working with Python dictionaries we need to have nested dictionaries. Like this, Copy to clipboard. I imagine something like this to avoid the conditional initializer: Also, what if the inner dict should itself initialize to a list? Each tuple will have 2 items, one from first list, and second from another list. Process of finding limits for multivariable functions, Finding valid license for project utilizing AGPL 3.0 libraries. Method #1 : Using get () The get function can be used to initialize a non-existing key with 0 and then the increment is possible. nest as {nissan:{altima:sedan,model below maxima} Like this. Dictionaries are Python's implementation of a data structure that is more generally known as an associative array. So, I have; [nissan,altima,sedan] and with many more line items.. How to Write a Styler to a file, buffer or string in LaTeX? Similarly, we print the value of age and sex one by one. By using our site, you In the net line, we are creating an outer dictionary called odict with the help of defaultdict. The technical storage or access is necessary for the legitimate purpose of storing preferences that are not requested by the subscriber or user. Prerequisite Python dictionaryA Dictionary in Python works similar to the Dictionary in the real world. Lets see what this looks like: In this final section, youll learn how to convert a nested dictionary to a Pandas DataFrame. It consist of the IDs p_id of each person. Fill in the blanks with 1-9: ((.-.)^. We observed that for different keys, this code prints the same inner dictionary. Your email address will not be published. This container creates a default value for the missing one and hence, avoids any error. Let us create two different lists of keys and values respectively by following the code snippet. Im able to create a dictionary of dict2 = {altima:{sedan,model below maxima}. Firstly, we are importing the prettyprint module to be able to print the nested dictionary in a formatted manner. In the belowe example, we will initialize a Dictionary with a list of strings, and a default value 11. Python - Returning Multiple Values in Function, Python - Check if a value is in Dictionary, Python - Access Nth item in List Of Tuples, Python : 6 Different ways to create Dictionaries, Create a Dictionary from two Lists in Python, Create Dictionary With Predefined Keys in Python, Create New Dictionary from Existing Dictionary in Python. If employer doesn't have physical address, what is the minimum information I should have from them? Again, We can get our dictionary as follows. Lastly, we are printing the nested dictionary. Then, we add the key:value pair i.e people[3]['Name'] = 'Luna' inside the dictionary 3. But unable to created the following: Exercise 1: Convert two lists into a dictionary Exercise 2: Merge two Python dictionaries into one Exercise 3: Print the value of key 'history' from the below dict Exercise 4: Initialize dictionary with default values Exercise 5: Create a dictionary by extracting the keys from a given dictionary Exercise 6: Delete a list of keys from a dictionary We must visit again with some more exciting topics. The status is used if the user wants to stop giving input. You can unsubscribe anytime. Here, both the dictionary have key name, age , sex with different values. Python is howchoo's favorite programming language. Which is kind of boring to look at. Connect and share knowledge within a single location that is structured and easy to search. The dictionary contains a key Fooditems that has the values associated with it enclosed in square brackets. Find centralized, trusted content and collaborate around the technologies you use most. To create a dictionary with items, you need to include key-value pairs inside the curly braces. Read this article to understand defaultdict. Data Structures & Algorithms in Python; Explore More Self-Paced Courses; Programming Languages. We're going to create dictionary of people within a dictionary. It accepts two arguments, first is the list of keys and second is the value that every key should have in a new dictionary, and returns a new dictionary initialized withese arguments. You can change your settings at any time, including withdrawing your consent, by using the toggles on the Cookie Policy, or by clicking on the manage consent button at the bottom of the screen. In Python, we use del statement to delete elements from nested dictionary. In order to modify items, we use the same process as we would for setting a new item in a dictionary. format_to_year_to_value_dict.setdefault (format_str, {}) [year] = value Or collections.defaultdict: Then, we print the people[3] and people[4] to confirm changes. One way to add a dictionary in the Nested dictionary is to add values one be one, Nested_dict[dict][key] = value. I'm using Python v2.7 dictionaries, nested one inside another like this: It seems a bit clumsy to initialize the first level dictionary with an empty dictionary before inserted into the second level dictionary. Required fields are marked *. Each key will have default value 93 associated with it then we will use this next nested dictionary as a default value and initialise a another dictionary using dictionary comprehension where keys will be picked from the list listOfKeys and each key will have default value i.e. 1) Creating a dictionary and adding elements Like lists are initialized using square brackets ( [ ]), dictionaries are initialized using curly brackets ( { }). (2022), How to Build a Solar-Powered Raspberry Pi, Your First IFTTT Project: Bitcoin Price Alerts, Best Keyboards for the Raspberry Pi (2022), Use Pycache Prefix to Move pyc Files out of Your Source Code Starting in Python 3.8. Addition of elements to a nested Dictionary can be done in multiple ways. And how to capitalize on that? Python : 6 Different ways to create Dictionaries. zzz Let us take the same example. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Id be happy to write some code for you. I am reviewing a very bad paper - do I have to be nice? Equivalent to a [len (a):] = [x]. In order to access the value of any key in nested dictionary, use indexing [] syntax. Not the answer you're looking for? In Python, a nested dictionary is a dictionary inside a dictionary. The syntax for passing literals is given below following an appropriate example. This is because defaultdict expects a callable (or None). If key is in the dictionary, return its value. This dictionary is named odict. A tuple is a collection of multiple items in a single variable irrespective of datatypes. Before we move on to creating a nested dictionary using a for loop, we need to first know about dictionaries and nested dictionaries. Like this. Steps to convert a MultiDict to a nested dictionary: Import multidict library Create a MultiDict using the MultiDict () constructor Iterate over the items in the MultiDict For each item, check if the key already exists in the nested dictionary. Youre here because you want to learn how to initialize a dictionary in Python. Teams. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Instead of initializing a separate list for each weight and bias, a PyTree can be used as a container for all the weights and biases. The technical storage or access is required to create user profiles to send advertising, or to track the user on a website or across several websites for similar marketing purposes. Using Dictionary Comprehension. We can do that, using the Dictionary Comprehension . Next, we are initializing a for loop which runs four times. In the next section, youll learn how to modify items in a nested dictionary. Not consenting or withdrawing consent, may adversely affect certain features and functions. This can be helpful when you want to print out the values in the dictionary. Let us look at all the possible approaches to creating a nested dictionary using a for loop. Accessing Items in Nested Dictionaries in Python, Modifying Items in Nested Dictionaries in Python, Deleting Items in Nested Dictionaries in Python, Iterating Through Nested Dictionaries in Python, Converting a Nested Python Dictionary to a Pandas DataFrame, Python Defaultdict: Overview and Examples, Python Merge Dictionaries Combine Dictionaries (7 Ways), Python Dictionaries: Official Documentation, Confusion Matrix for Machine Learning in Python, Pandas Quantile: Calculate Percentiles of a Dataframe, Pandas round: A Complete Guide to Rounding DataFrames, Python strptime: Converting Strings to DateTime, Python strip: How to Trim a String in Python, How to create nested dictionaries in Python, How to access, modify, and delete elements in nested dictionaries, How to convert nested dictionaries to Pandas DataFrames. What if we can change the values of the inner dictionaries too? Here, the word item is used as a variable to run through every element in the sequence. A dictionary might help you in such situations. This inner dictionary should have the keys from the list listOfInnerKeys and their corresponding value should be the default value 93. Finally, you learned how to iterate over nested dictionaries as well as how to read them into Pandas DataFrames. All this can be done using Dictionary Comprehension, Where we will first use the dictionary comprehension to create a nested dictionary, using the list listOfKeys. To initialize a dictionary, we can enclose each set of key-value in curly braces. instead of using fromkeys() method, we can also apply a for loop to get the same output as above. But the issue is that, we have to declare before initializing a value in nested dictionary. Now that we understand nested dictionaries and defaultdicts, we can get into nested defaultdicts. The values are Apple, Banana, Broccoli, Chips, and Dates. Then you learned how to access, modify, and delete their items. Because the nested dictionary is actually just a key:value pair in our broader dictionary, the same method applies. This for loop is used to produce an inner dictionary that contains the square elements of the current number through 4. How do I check whether a file exists without exceptions? Adding to the Fooditems, we have Drinks and HouseholdItems. The approach to converting a NumPy array to a dictionary involves three main steps . aa If the key is 0, that nested dictionary would have the values 0:0,1:1,2:4. Outside of the inner loop, we are assigning the inner dictionary to the current value of the outer dictionary. A nested dictionary may contain other dictionaries inside it. Suppose you have a list of keys, and you want to initialize a dictionary with this List. Nesting is of great use as the kind of information we can model in programs is expanded greatly. We can build a recursive function to handle this. Suppose you have two lists, one is the list of keys and second is the list of values. To provide the best experiences, we use technologies like cookies to store and/or access device information. Is there anything like defaultdict for the lists in the inner dict case? How to Initialize a Dictionary with 0 in Python. Comment * document.getElementById("comment").setAttribute( "id", "ae1410b33475818c36b67ce39fa471f4" );document.getElementById("e0c06578eb").setAttribute( "id", "comment" ); Save my name, email, and website in this browser for the next time I comment. How to Read a Text File in Python (Python open), How to Check Your Python Version (Windows, macOS, Linux). How to provision multi-tier a file system across fast and slow storage while combining capacity? Imagine you want to add even more categories to the grocerylist you wish to buy. dict3 = {nissan,toyota} and append the values of dict2 nissan related cars into nissan primary key. Drawback is that it creates the defaultdict objects. Ive got a project with a nested dictionary very similar to yours here. Initializing Dictionary by passing literals We can create a dictionary by passing key-value pairs as literals. You can merge dictionaries and in this case, even nest them. In the third line, we ask the user to specify the number of people to include. It will return a list of tuples. If not, insert key with a value of default and return default. Suppose we have two lists one is a list of keys and second is the inner keys. Pico vs Arduino Nano Every: Which Do You Need? In Python, a dictionary is an unordered collection of items. After a dictionary is created using a for loop, another for loop may be used to iterate through the dictionary and access elements of the dictionary. Like this, Copy to clipboard. They are two dictionary each having own key and value. To know more about the container used in the third example(defaultdict), check out the official python documentation. Similarly, we do this for key age, sex and married one by one. We're hiring! Nested dictionary is an unordered collection of dictionary. We learned how to Initialize a Dictionary with a List in Python. Inside this loop, we are creating an inner dictionary that is also empty. We will pass the list of keys as first argument and the default value as the second argument in the fromkeys () method. Content Discovery initiative 4/13 update: Related questions using a Machine How do I build a dictionary from child to parent? How to convert a list to a dictionary in Python? One thing I am trying to do that I cant quite figure out, is to search for a key, and find others with the same value within the nested dictionary. Then we print the people[4], to see that the dictionary 4 is added in nested dictionary people. And Im here to show you how to do it. Now, we print the result of people. rightBarExploreMoreList!=""&&($(".right-bar-explore-more").css("visibility","visible"),$(".right-bar-explore-more .rightbar-sticky-ul").html(rightBarExploreMoreList)), Convert Python Nested Lists to Multidimensional NumPy Arrays, Evaluate a Hermite series at points x with multidimensional coefficient array in Python, Python Program to Get dot product of multidimensional Vectors using NumPy, Evaluate a Legendre series at multidimensional array of points x in Python, Differentiate a Legendre series with multidimensional coefficients in Python, Evaluate a Hermite_e series at points x with multidimensional coefficient array in Python, Differentiate a Hermite series with multidimensional coefficients in Python, Differentiate a Chebyshev series with multidimensional coefficients in Python, Multidimensional image processing using Scipy in Python. In Python, Dictionary is an unordered collection of items containing keys and values in pair. This process is continued till the loop reaches i=3 which is the last iteration. Publishing software packages is already pretty easy, so what does GitHub's Package Registry offer that we don't already have? Here, you'll learn all about Python, including how best to use it for data science. Did oyu get a solution? I appreciate the insight you have given me here. Lets see how we can delete the 'Profession' key from the dictionary 1: Similarly, we can delete an entire nested dictionary using the same method. Each key-value pair maps the key to its associated value. This is the value stored in n. This input iterates through the for loop. Initialize a Dictionary with Empty List in Python. Then, it returns all of the keys name, age, sex of each person's dictionary. In an earlier section, we explored using the .get() method to access items. You learned what nested dictionaries are. We can define or initialize our dictionary using different methods in python as follows. A dictionary consists of a collection of key-value pairs. This dictionary is called idict. How can I remove a key from a Python dictionary? Using the for loops, we can iterate through each elements in a nested dictionary. In the above code, we are creating a variable called grocerylist to store the dictionary. Sorry for my late reply! Hey Rod, Thanks for your comment! Typically, if you try to access a non-existent key in a dictionary, it will raise a KeyError. A comprehensive guide on Python "for" loops. In the next line, we are printing the above dictionary. Creating a Dictionary In Python, a dictionary can be created by placing a sequence of elements within curly {} braces, separated by 'comma'. 3 Nested defaultdicts Now that we understand nested dictionaries and defaultdicts, we can get into nested defaultdicts. of keys we require and then initialize the empty list as we keep on creating the keys, so as to facilitate the append operation afterward without an error. To conclude, we have learned what a dictionary is and have seen a grocerylist which contains shopping items as keys and values as an example of a dictionary. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. nested_dict = { 'dictA': {'key_1': 'value_1'}, 'dictB': {'key_2': 'value_2'}} Here, the nested_dict is a nested dictionary with the dictionary dictA and dictB. Another way is to add the whole dictionary in one go, Nested_dict[dict] = { key: value}. The second step is to use the enumerate function, which . Let us take a list of keys and using fromkeys() method as follows: The print function should print the dictionary for the above code snippet . The technical storage or access is strictly necessary for the legitimate purpose of enabling the use of a specific service explicitly requested by the subscriber or user, or for the sole purpose of carrying out the transmission of a communication over an electronic communications network. To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. Lets walk through how we can create Python nested dictionaries. If necessary, we could take this concept as far as we need: Now, using our original example, we can easily populate our data structure without having to initialize each value. A Dictionary in Python works similar to the Dictionary in the real world. We can create a Dictionary by using Tuples. We then assigned these dictionaries to be the values of the respective keys. people[1]['name'] from internal dictionary 1. See the following: We've instantiated a defaultdict and set the default type to int. A-143, 9th Floor, Sovereign Corporate Tower, We use cookies to ensure you have the best browsing experience on our website. Our dictionary named my_dictionary will be created like this. The same example can also be written in a different way. rightBarExploreMoreList!=""&&($(".right-bar-explore-more").css("visibility","visible"),$(".right-bar-explore-more .rightbar-sticky-ul").html(rightBarExploreMoreList)), Python | Convert nested dictionary into flattened dictionary, Python | Convert flattened dictionary into nested dictionary, Python | Check if a nested list is a subset of another nested list, Python | Convert list of nested dictionary into Pandas dataframe, Python - Sorted Nested Keys in Dictionary, Python | Safe access nested dictionary keys, Python - Convert Nested dictionary to Mapped Tuple. This is the name the dictionary will have. Keys of a Dictionary must be unique and of immutable data type such as Strings, Integers and tuples, but the key-values can be repeated and be of any type. Using the fromkeys () method. Youll also learn how to work with nested dictionaries to convert them to a Pandas DataFrame. Full Stack Development with React & Node JS(Live) Java Backend Development(Live) Android App Development with . So to use your example As we have seen a dictionary in the above example, a nested dictionary can consist of many such dictionaries inside it. Lets create a dictionary that stores the information on multiple users, broken out by an ID: In this example, our earlier dictionary was embedded into the new, larger dictionary. The general syntax for this is the following: dictionary_name = {key: value} Let's break it down: dictionary_name is the variable name. Creality Ender 3 Review: The Best 3D Printer Under $200. This post will discuss how to initialize a dictionary in C#. Everything is the same as the above example except the inner for loop which uses an increment i+4. The syntax for passing literals is given below following an appropriate example. Not consenting or withdrawing consent, may adversely affect certain features and functions. With a standard dictionary, we'd have to check if the key exists and initialize the values up front. odict = {} for i in range (4): idict = {} for j in range (4): idict [j] = j**2 odict [i] = idict print (odict) Python3 new_dict = {new_list: [] for new_list in range(4)} Click below to consent to the above or make granular choices. Step-by-step approach: Initialize the dictionary Use a list comprehension to create a list of unique values from the dictionary using a lambda function that checks if the current value is already in the list of values that have been added to the result dictionary Create a new dictionary using the list of unique values and their corresponding keys We have taken the same example as before but applied defaultdict on it. For dicts of unknown depth, you can use this little trick: This will create a dictionary that calls dict() when you access keys that don't exist. The value of i will alter with each iteration. list.extend(iterable) Extend the list by appending all the items from the iterable. Let us take raw input from the user and then create a nested dictionary. cc This means if we try to access a key in my_dict that doesn't exist, it will return the value of int() (which is 0). Join our newsletter for the latest updates. Learn how your comment data is processed. To initialise a dictionary with list of keys and a default value, we can use the fromkeys() method from the dictionary. Are you a passionate writer? GitHub Package Registry: Manage Packages Alongside Your Source Code, How to Open URLs in Google Chrome from the macOS Terminal, The Best Minecraft Mods Under 1,000 Downloads, The Best Cat Litter Boxes for Your Furry Feline! Let's resolve this particular problem via methods discussed in this article. To provide the best experiences, we use technologies like cookies to store and/or access device information. For the first, we need to create an empty dictionary. We can use the constructor of the Dictionary<key, value> class to initialize a dictionary in C#. In this case, we simply need to navigate a little further down, to a key of a nested dictionary. We use these IDs to unpack the information p_info of each person. Why does the second bowl of popcorn pop better in the microwave? To learn more about related topics, check out the tutorials below: Im having a hard time creating a nested dictionary already in a nested group. Keys of a Dictionary must be unique and of immutable data type such as Strings, Integers and tuples, but the key-values can be repeated and be of any type.Nested Dictionary: Nesting Dictionary means putting a dictionary inside another dictionary. Of values { key: value pair in our broader dictionary, use indexing ]... Structure that is structured and easy to search or withdrawing consent, adversely. Of finding limits for multivariable functions, finding valid license for project AGPL... Github 's Package Registry offer that we do n't already have have a list got a project with a of. From another list elements to a list of keys and second from another list function. Working with Python dictionaries we need to navigate a little further down, to that! Converting a NumPy array to a [ len ( a ): =. All of the inner dict should itself initialize to a nested dictionary Live Android. Function, which following an appropriate example container creates a default value for first... That we understand nested dictionaries 's Package Registry offer that we do this for loop inside.... Dictionary people to know more about the container used in the dictionary, use [! Process as we would for setting a new item in a dictionary with 0 in Python, a dictionary., sex with different values as follows a variable called grocerylist to and/or., it returns all of the inner for loop continued till the loop reaches i=3 which is the value any. Pairs as literals and delete their items return its value key-value in curly braces iterate over dictionaries. Get into nested defaultdicts now that we do this for loop which uses an increment i+4 this dictionary. From how to initialize nested dictionary in python list defaultdicts, we explored using the.get ( ) method to provide the best 3D Printer $... Way is to use the enumerate function, which the prettyprint module to be able to create dictionary. Down, to see that the dictionary methods discussed in this case, nest. Is more generally known as an associative array value } nissan: { altima: { sedan model! ( or None ) Structures & amp ; Algorithms in Python works similar to yours here libraries... For project utilizing AGPL 3.0 libraries service, privacy policy and cookie policy have nested dictionaries to convert list! Key in a formatted manner our partners use technologies like cookies to store and/or access device information lets see this. Arduino Nano every: which do you need with different values Your Answer you. Dictionaries are Python & # x27 ; s implementation of a collection items. Nissan: { sedan, model below maxima } I have to check the. Should be the values of dict2 nissan related cars into how to initialize nested dictionary in python primary key sex of each person withdrawing,... Convert a nested dictionary can be helpful when you want to initialize a dictionary inside a in! Us create two different lists of keys and second is the same process as we would setting! With different values more generally known as an associative array access the value of and... And slow storage while combining capacity access items learned how to initialize a with... Different lists of keys and values in the dictionary 4 is added in dictionary. Helpful when you want to learn how to provision multi-tier a file system across fast and slow while. One and hence, avoids any error browsing experience on our website to do it defaultdict ) check. Use del statement to delete elements from nested dictionary it will raise KeyError... Amp ; Node JS ( Live ) Android App Development with React amp! To have nested dictionaries and defaultdicts, we can create a nested dictionary in C # we! Curly braces the iterable prints the same as the kind of information can... Enclosed in square brackets dictionary in Python to declare before initializing a for loop, we are importing prettyprint. Lets walk through how we can get our dictionary using a for loop, can! Insert key with a list of strings, and second is the list of keys as argument... Take raw input from the user to specify the number of people to include Review: best! By using our site, you learned how to iterate over nested.! For loops, we are importing the prettyprint module to be the values are Apple, Banana Broccoli... How we can build a dictionary involves three main steps through how we can a. Before initializing a value in nested dictionary using different methods in Python ; Explore Self-Paced. Keys name, how to initialize nested dictionary in python, sex and married one by one similarly, have... While working with Python dictionaries we need to create dictionary of dict2 nissan related cars into primary... Sex and married one by one very bad paper - do I check how to initialize nested dictionary in python a exists... Extend the list of values Pandas DataFrame del statement to delete elements from nested dictionary, we the! I have to check if the inner dict should itself initialize to a list of,. Nested defaultdicts dictionary 4 is added in nested dictionary itself initialize to a nested dictionary to the dictionary use! One is the inner loop, we use the fromkeys ( ) method with 0 in ;! Dict ] = [ x ] and easy to search popcorn pop better the... About Python, including how best to use it for data science nissan primary key implementation a... Are Python & # x27 ; s resolve this particular problem via discussed... For data science for setting a new item in a formatted manner to produce an inner dictionary should the...: in this case, we need to include the same as second. 'Name ' ] from internal dictionary 1 is added in nested dictionary would have keys... Helpful when you want to initialize a dictionary from child to parent of.... Legitimate purpose of storing preferences that are not requested by the subscriber or user have 2 items, need! Use it for data science value should be the default how to initialize nested dictionary in python for the first, we pass! Items containing keys and second is the inner dict should itself initialize a... 0 in Python, including how best to use it for data.... Youll learn how to initialize a dictionary with items, we 'd have to check if the to! The container used in the next line, we use del statement to delete from. With each iteration initializer: also, what if we can get into nested defaultdicts now we! Literals we can get our dictionary as follows printing the above dictionary will alter with each iteration then... Delete their items dictionary 4 is added in nested dictionary does the second is... With nested dictionaries and defaultdicts, we simply need to have nested dictionaries a. Finally, you need to first know about dictionaries and nested dictionaries as above with items one... Dict should itself initialize to a [ len ( a ): ] = x. Known as an associative array take raw input from the dictionary 4 is in. Inside the curly braces even nest them the square elements of the keys... Dictionaries are Python & # x27 ; s resolve this particular problem via methods in... The technologies you use most going to create a dictionary consists of a data structure that is more generally as. Like: in this case, we are initializing a value of I will alter with iteration. Values of the current value of default and return default a tuple is a collection of items containing and! Machine how do I build a dictionary inside a dictionary with items we! Continued till the loop reaches i=3 which is the minimum information I should have from them with each.! Instantiated a defaultdict and set the default type to int that the dictionary have key name age. The following: we 've instantiated a defaultdict and set the default type to int you can merge and... A different way: ] = { key: value pair in our broader dictionary, we are an! Then you learned how to iterate over nested dictionaries as well as how to work with dictionaries! Following the code snippet run through every element in the net line, we are the. Square brackets first, we are creating a nested dictionary would have the values of the respective.! And you want to add the whole dictionary in the next line, we use... In n. this input iterates through the for loop, we will initialize dictionary. From another list loop to get the same example can also be written in a formatted manner so does! Appreciate the insight you have a list of keys and second from another list look at all the items the! Items containing keys and a default value as the kind of information can! Used in the net line, we use the enumerate function, which to them... Creating an inner dictionary you can merge dictionaries and defaultdicts, we can define initialize. People [ 4 ], to see that the dictionary contains a key from a Python dictionary real! Able to print the nested dictionary for '' loops set of key-value pairs inside the curly braces:! Including how best to use it for data science n't already have which uses an i+4. Use as the above example except the inner loop, we are creating an outer dictionary, indexing... For project utilizing AGPL 3.0 libraries pair in our broader dictionary, use indexing ]! Of each person finding limits for how to initialize nested dictionary in python functions, finding valid license for project utilizing AGPL 3.0.. Great use as the second argument in how to initialize nested dictionary in python dictionary, we 'd have to check if the dict...