Data structures are formats that we can use to keep track of our data in an organized fashion.
- one very basic data structure
- Programmers use lists as a container to store multiple pieces of information that relate to each other in some way.
- orders data in a specific, linear sequence
Access Items in a List
- order items so that they’re in a specific sequence.
Index (or indices – plural) is the position of value in a list. It’s like an address that we use to locate an item in a list. It’s a number that starts at 0.
Add Items to a List
Append to the end of the list – add things to the end of an existing list
myList = ['apple', 'banana', 'pear'] myList.append('orange') // now, myList == ['apple', 'banana', 'pear', 'orange']
Add item to an existing list, with index number for where we want to position our new value.
myList = ['apple', 'banana', 'pear'] myList.splice(1, 0, 'mango') // make 'mango' the second item in the list // now, myList = ['apple', 'mango', 'banana', 'pear']
Removing Items from a List
Remove last item.
myList = ['apple', 'banana', 'pear'] // removes 'pear' from myList and returns 'pear' myList.pop() // now, myList == ['apple', 'banana']
Remove items from the middle:
myList = ['apple', 'banana', 'pear'] myList.splice(1, 1) // removes 'banana' from myList and returns 'banana' // now, myList == ['apple', 'pear']
myList), then setting it equal to a set of brackets
. If there’s nothing in between the brackets, the list is empty. But
myList has three items in between brackets
, each separated by a comma
myList = ['apple', 'banana', 'pear']
You may have noticed that those were all strings. We can also put other data types in a list, including numbers and boolean values. We can even put other lists in a list!
To select an item:
myList =  I am selecting the first item from the list or 'apple'
colors = ['red', 'yellow', 'green', 'blue']
To select the third item in the list, we would write
// the following line will return 'green'
We could also save this selection to a variable, so we can use it later in our code:
// now myFavoriteColor is equal to 'green'
myFavoriteColor = colors
// Build a list comicStrip = ['Codey sees the trail', 'Codey starts the hike', 'Codey is halfway', 'Codey reaches the finish'] // select the 4th item from the list selection = comicStrip // and save it to the variable selection
The larger the sample size and the more diverse your dataset is, the more confident you’ll be in your results.
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