An Elementary Introduction to the Wolfram Language
3First Look at Lists
Lists are a basic way to collect things together in the Wolfram Language. {1,2,3} is a list of numbers. On their own, lists dont do anything; theyre just a way to store things. So if you give a list as input, itll just come back unchanged:
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ListPlot is a function that makes a plot of a list of numbers.
Plot the list of numbers {1, 1, 2, 2, 3, 4, 4}:
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Plot the list of numbers {10, 9, 8, 7, 3, 2, 1}:
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Range is a function that makes a list of numbers.
Generate a list of numbers up to 10:
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Reverse reverses the elements in a list.
Reverse the elements in a list:
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Reverse what Range has generated:
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Plot the reversed list:
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Join joins lists together, making a single list as the result.
Join lists together:
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Join two lists made by Range:
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Reverse the list in the middle:
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{1,2,3,4} list of elements
ListPlot[{1,2,3,4}] plot a list of numbers
Range[10] range of numbers
Reverse[{1,2,3}] reverse a list
Join[{4,5,6},{2,3,2}] join lists together
3.1Use Range to create the list {1, 2, 3, 4}»
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3.2Make a list of numbers up to 100. »
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3.3Use Range and Reverse to create {4, 3, 2, 1}»
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3.4Make a list of numbers from 1 to 50 in reverse order. »
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3.5Use Range, Reverse and Join to create {1, 2, 3, 4, 4, 3, 2, 1}»
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3.6Plot a list that counts up from 1 to 100, then down to 1. »
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3.7Use Range and RandomInteger to make a list with a random length up to 10. »
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3.9Find a simpler form for Join[{1, 2}, Join[{3, 4}, {5}]]»
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3.10Find a simpler form for Join[Range[10], Join[Range[10], Range[5]]]»
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3.11Find a simpler form for Reverse[Join[Range[20], Reverse[Range[20]]]]»
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+3.1Compute the reverse of the reverse of {1, 2, 3, 4}»
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+3.2Use Range, Reverse and Join to create the list {1, 2, 3, 4, 5, 4, 3, 2, 1}»
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+3.3Use Range, Reverse and Join to create {3, 2, 1, 4, 3, 2, 1, 5, 4, 3, 2, 1}»
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+3.4Plot the list of numbers {10, 11, 12, 13, 14}»
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+3.5Find a simpler form for Join[Join[Range[10], Reverse[Range[10]]], Range[10]]»
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Usually list 1 2 3. { and } are called braces or curly brackets. { is open brace and } is close brace.
Is a list a function?
Yes. {1, 2, 3} is List[1, 2, 3]. But unlike, say, Plus, the function List doesnt actually compute anything; it just comes back unchanged.
What is ListPlot plotting?
The values of successive list elements. The x value of each point gives the position in the list; the y value gives the value of that element.
How long can lists be?
As long as you want, until your computer runs out of memory.
 
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