范围 #

r1 = 1:5
r2 = 1:10
r3 = 'a':'z'
r4 = 0.0:0.1:1.0

typeof(1:5)
typeof(1:2:10)
typeof(0.0:0.1:1.0)
typeof('a':'z')

r = 1:10^9
length(r)
first(r)
last(r)

r = 1:10
typeof(r)
step(r)

r = 1:2:10
typeof(r)
step(r)
collect(r)

r = 0.0:0.1:1.0
typeof(r)
step(r)
length(r)
collect(r)

r = LinRange(0, 1, 11)
typeof(r)
collect(r)

r = 1:2:10
first(r)
last(r)
step(r)
length(r)
minimum(r)
maximum(r)

r = 1:2:10
r[1]
r[3]
r[end]
r[2:4]

r = 1:2:10
5 in r
6 in r
in(5, r)
in(6, r)

r1 = 1:5
r2 = 3:7

intersect(r1, r2)
union(r1, r2)
setdiff(r1, r2)

for i in 1:5
    println(i)
end

for i in 1:2:10
    println(i)
end

for (i, x) in enumerate(1:3:10)
    println("$i: $x")
end

r = 1:5
iterate(r)
iterate(r, 1)
iterate(r, 2)

arr = [10, 20, 30, 40, 50]
arr[1:3]
arr[2:2:end]
arr[end:-1:begin]

[i^2 for i in 1:5]
[i * j for i in 1:3, j in 1:3]
zeros(5)
ones(3, 3)
rand(2, 3)

for i in 1:100
    if i % 10 == 0
        println(i)
    end
end

mat = [1 2 3; 4 5 6; 7 8 9]
mat[1:2, 2:3]
mat[:, 1]
mat[1, :]

range(1, length=5)
range(1, stop=10, length=5)
range(1, stop=10, step=2)
range(1, step=2, length=5)

r = Base.OneTo(5)
typeof(r)
collect(r)

arr = [1 2 3; 4 5 6]
axes(arr)
axes(arr, 1)
axes(arr, 2)

arr = [10, 20, 30, 40, 50]
for i in eachindex(arr)
    println("$i: $(arr[i])")
end

r = 1:5
sum(r)
mean(r)

[2^i for i in 0:5]

using LinearAlgebra
r = LinRange(0, 2π, 100)
sin.(r)

function sum_range(start, stop, step=1)
    sum(start:step:stop)
end

sum_range(1, 100)
sum_range(1, 100, 2)

function fibonacci_range(n)
    a, b = 0, 1
    result = Int[]
    for _ in 1:n
        a, b = b, a + b
        push!(result, a)
    end
    return result
end

fibonacci_range(10)

function grid_coordinates(x_range, y_range)
    [(x, y) for x in x_range, y in y_range]
end

grid_coordinates(1:3, 1:2)

function time_series(start_time, end_time, step_seconds)
    start_seconds = start_time.hour * 3600 + start_time.minute * 60 + start_time.second
    end_seconds = end_time.hour * 3600 + end_time.minute * 60 + end_time.second
    
    times = []
    for s in start_seconds:step_seconds:end_seconds
        h, s = divrem(s, 3600)
        m, s = divrem(s, 60)
        push!(times, (hour=h, minute=m, second=s))
    end
    return times
end

using Dates
time_series(Time(9, 0, 0), Time(9, 30, 0), 300)