Python – Copy Dictionaries

Copy a Dictionary

You cannot copy a dictionary simply by typing dict2 =
dict1, because: dict2 will only be a reference to dict1, and changes made in dict1 will automatically also be made in dict2.

There are ways to make a copy, one way is to use the built-in Dictionary method
copy().

Example

Make a copy of a dictionary with the copy() method:

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
mydict = thisdict.copy()
print(mydict)

Another way to make a copy is to use the built-in function dict(). Continue reading Python – Copy Dictionaries

Python – Loop Dictionaries

Loop Through a Dictionary

You can loop through a dictionary by using a for loop.

When looping through a dictionary, the return value are the keys of the dictionary, but there are methods to return the values as well.

Example

Print all key names in the dictionary, one by one:

for x in thisdict:
  print(x)

Continue reading Python – Loop Dictionaries

Python – Remove Dictionary Items

Removing Items

There are several methods to remove items from a dictionary:

Example

The pop() method removes the item with the specified key name:

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
thisdict.pop("model")
print(thisdict)

Continue reading Python – Remove Dictionary Items

Python – Add Dictionary Items

Adding Items

Adding an item to the dictionary is done by using a new index key and assigning a value to it:

Example

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
thisdict["color"] = "red"
print(thisdict)

Continue reading Python – Add Dictionary Items

Python – Change Dictionary Items

Change Values

You can change the value of a specific item by referring to its key name:

Example

Change the “year” to 2018:

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
thisdict["year"] = 2018

Continue reading Python – Change Dictionary Items

Python – Access Dictionary Items

Accessing Items

You can access the items of a dictionary by referring to its key name, inside square brackets:

Example

Get the value of the “model” key:

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}
x = thisdict["model"]

There is also a method called get() that will give you the same result: Continue reading Python – Access Dictionary Items

Python Dictionaries

thisdict = {
  "brand": "Ford",
  "model": "Mustang",
  "year": 1964
}

Dictionary

Dictionaries are used to store data values in key:value pairs.

A dictionary is a collection which is ordered*, changeable and do not allow duplicates.

As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.

Continue reading Python Dictionaries

Python – Set Methods

Set Methods

Python has a set of built-in methods that you can use on sets.

Method Shortcut Description
add() Adds an element to the set
clear() Removes all the elements from the set
copy() Returns a copy of the set
difference() – Returns a set containing the difference between two or more sets
difference_update() -= Removes the items in this set that are also included in another, specified set
discard() Remove the specified item
intersection() & Returns a set, that is the intersection of two other sets
intersection_update() &= Removes the items in this set that are not present in other, specified set(s)
isdisjoint() Returns whether two sets have a intersection or not
issubset() <= Returns whether another set contains this set or not
issubset() < Returns whether all items in this set is present in other, specified set(s)
issuperset() >= Returns whether this set contains another set or not
> Returns whether all items in other, specified set(s) is present in this set
pop() Removes an element from the set
remove() Removes the specified element
symmetric_difference() ^ Returns a set with the symmetric differences of two sets
symmetric_difference_update() ^= Inserts the symmetric differences from this set and another
union() | Return a set containing the union of sets
update() |= Update the set with the union of this set and others

Python – Join Sets

Join Sets

There are several ways to join two or more sets in Python.

The union() and update() methods joins all items from both sets.

The intersection() method keeps ONLY the duplicates.

The difference() method keeps the items from the first set that are not in the other set(s).

The symmetric_difference() method keeps all items EXCEPT the duplicates. Continue reading Python – Join Sets

Python – Loop Sets

Loop Items

You can loop through the set items by using a for loop:

Example

Loop through the set, and print the values:

thisset = {"apple", "banana", "cherry"}

for x in thisset:
  print(x)

Continue reading Python – Loop Sets