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ry to use as few words as possible
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@ -170,10 +170,12 @@ push!(a, 3) # => [1,2,4,3]
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append!(a, b) # => [1,2,4,3,4,5,6]
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append!(a, b) # => [1,2,4,3,4,5,6]
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# Remove from the end with pop
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# Remove from the end with pop
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pop!(b) # => 6 and b is now [4,5]
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pop!(b) # => 6
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b # => [4,5]
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# Let's put it back
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# Let's put it back
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push!(b, 6) # b is now [4,5,6] again.
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push!(b, 6) # => [4,5,6]
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b # => [4,5,6]
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a[1] # => 1 # remember that Julia indexes from 1, not 0!
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a[1] # => 1 # remember that Julia indexes from 1, not 0!
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@ -182,14 +184,18 @@ a[1] # => 1 # remember that Julia indexes from 1, not 0!
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a[end] # => 6
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a[end] # => 6
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# we also have popfirst! and pushfirst!
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# we also have popfirst! and pushfirst!
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popfirst!(a) # => 1 and a is now [2,4,3,4,5,6]
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popfirst!(a) # => 1
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a # => [2,4,3,4,5,6]
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pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
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pushfirst!(a, 7) # => [7,2,4,3,4,5,6]
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a # => [7,2,4,3,4,5,6]
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# Function names that end in exclamations points indicate that they modify
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# Function names that end in exclamations points indicate that they modify
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# their argument.
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# their argument.
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sort(arr) # => [4,5,6]; arr is still [5,4,6]
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sort!(arr) # => [4,5,6]; arr is now [4,5,6]
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arr = [5,4,6] # => 3-element Array{Int64,1}: [5,4,6]
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arr = [5,4,6] # => 3-element Array{Int64,1}: [5,4,6]
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sort(arr) # => [4,5,6]
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arr # => [5,4,6]
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sort!(arr) # => [4,5,6]
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arr # => [4,5,6]
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# Looking out of bounds is a BoundsError
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# Looking out of bounds is a BoundsError
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try
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try
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@ -227,11 +233,13 @@ a[2:end] # => [2, 3, 4, 5]
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# Remove elements from an array by index with splice!
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# Remove elements from an array by index with splice!
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arr = [3,4,5]
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arr = [3,4,5]
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splice!(arr, 2) # => 4 ; arr is now [3,5]
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splice!(arr, 2) # => 4
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arr # => [3,5]
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# Concatenate lists with append!
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# Concatenate lists with append!
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b = [1,2,3]
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b = [1,2,3]
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append!(a, b) # Now a is [1, 2, 3, 4, 5, 1, 2, 3]
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append!(a, b) # => [1, 2, 3, 4, 5, 1, 2, 3]
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a # => [1, 2, 3, 4, 5, 1, 2, 3]
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# Check for existence in a list with in
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# Check for existence in a list with in
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in(1, a) # => true
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in(1, a) # => true
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@ -240,8 +248,9 @@ in(1, a) # => true
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length(a) # => 8
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length(a) # => 8
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# Tuples are immutable.
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# Tuples are immutable.
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tup = (1, 2, 3) # => (1,2,3) # an (Int64,Int64,Int64) tuple.
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tup = (1, 2, 3) # => (1,2,3)
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tup[1] # => 1
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typeof(tup) # => Tuple{Int64,Int64,Int64}
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tup[1] # => 1
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try
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try
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tup[1] = 3
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tup[1] = 3
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# => ERROR: MethodError: no method matching
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# => ERROR: MethodError: no method matching
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@ -251,23 +260,30 @@ catch e
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end
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end
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# Many array functions also work on tuples
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# Many array functions also work on tuples
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length(tup) # => 3
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length(tup) # => 3
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tup[1:2] # => (1,2)
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tup[1:2] # => (1,2)
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in(2, tup) # => true
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in(2, tup) # => true
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# You can unpack tuples into variables
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# You can unpack tuples into variables
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a, b, c = (1, 2, 3) # => (1,2,3) # a is now 1, b is now 2 and c is now 3
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a, b, c = (1, 2, 3) # => (1,2,3)
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a # => 1
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b # => 2
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c # => 3
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# Tuples are created even if you leave out the parentheses
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# Tuples are created even if you leave out the parentheses
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d, e, f = 4, 5, 6 # => (4,5,6)
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d, e, f = 4, 5, 6 # => (4,5,6)
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d # => 4
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e # => 5
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f # => 6
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# A 1-element tuple is distinct from the value it contains
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# A 1-element tuple is distinct from the value it contains
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(1,) == 1 # => false
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(1,) == 1 # => false
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(1) == 1 # => true
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(1) == 1 # => true
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# Look how easy it is to swap two values
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# Look how easy it is to swap two values
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e, d = d, e # => (5,4) # d is now 5 and e is now 4
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e, d = d, e # => (5,4)
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d # => 5
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e # => 4
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# Dictionaries store mappings
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# Dictionaries store mappings
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empty_dict = Dict() # => Dict{Any,Any} with 0 entries
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empty_dict = Dict() # => Dict{Any,Any} with 0 entries
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@ -419,7 +435,9 @@ function add(x, y)
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x + y
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x + y
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end
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end
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add(5, 6) # => 11 after printing out "x is 5 and y is 6"
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add(5, 6)
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# => x is 5 and y is 6
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# => 11
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# Compact assignment of functions
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# Compact assignment of functions
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f_add(x, y) = x + y # => f_add (generic function with 1 method)
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f_add(x, y) = x + y # => f_add (generic function with 1 method)
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