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genkuroki/Iterators.ipynb

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Iterators
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Iterators.ipynb
{
"cells": [
{
"metadata": {},
"cell_type": "markdown",
"source": "https://docs.julialang.org/en/v1/base/iterators/"
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "iter1 = Iterators.repeated(\"hoge\")\niter1_take3 = Iterators.take(iter1, 3)\ncollect(iter1_take3)",
"execution_count": 1,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 1,
"data": {
"text/plain": "3-element Array{String,1}:\n \"hoge\"\n \"hoge\"\n \"hoge\""
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "iter2 = Iterators.countfrom(0)\niter2_take5 = Iterators.take(iter2, 5)\ncollect(iter2_take5)",
"execution_count": 2,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 2,
"data": {
"text/plain": "5-element Array{Int64,1}:\n 0\n 1\n 2\n 3\n 4"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "cat = Iterators.flatten((iter1_take3, iter2_take5))\ncollect(cat)",
"execution_count": 3,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 3,
"data": {
"text/plain": "8-element Array{Any,1}:\n \"hoge\"\n \"hoge\"\n \"hoge\"\n 0\n 1\n 2\n 3\n 4"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "iter3 = Iterators.countfrom(0x0)\niter3_take4 = Iterators.take(iter3, 4)\np = Iterators.product(iter3_take4, iter2_take5)\ncollect(p)",
"execution_count": 4,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 4,
"data": {
"text/plain": "4×5 Array{Tuple{UInt8,Int64},2}:\n (0x00, 0) (0x00, 1) (0x00, 2) (0x00, 3) (0x00, 4)\n (0x01, 0) (0x01, 1) (0x01, 2) (0x01, 3) (0x01, 4)\n (0x02, 0) (0x02, 1) (0x02, 2) (0x02, 3) (0x02, 4)\n (0x03, 0) (0x03, 1) (0x03, 2) (0x03, 3) (0x03, 4)"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "iter4 = Iterators.cycle([:red, :green, :blue])\niter4_take8 = Iterators.take(iter4, 8)\ncollect(iter4_take8)",
"execution_count": 5,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 5,
"data": {
"text/plain": "8-element Array{Symbol,1}:\n :red\n :green\n :blue\n :red\n :green\n :blue\n :red\n :green"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "x, state = iterate(iter4)",
"execution_count": 6,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 6,
"data": {
"text/plain": "(:red, 2)"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "x, state = iterate(iter4, state)",
"execution_count": 7,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 7,
"data": {
"text/plain": "(:green, 3)"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "x, state = iterate(iter4, state)",
"execution_count": 8,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 8,
"data": {
"text/plain": "(:blue, 4)"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "x, state = iterate(iter4, state)",
"execution_count": 9,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 9,
"data": {
"text/plain": "(:red, 2)"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "string.(iter4_take8)",
"execution_count": 10,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 10,
"data": {
"text/plain": "8-element Array{String,1}:\n \"red\"\n \"green\"\n \"blue\"\n \"red\"\n \"green\"\n \"blue\"\n \"red\"\n \"green\""
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "iter4_take8_not_red = Iterators.filter(x -> x != :red, iter4_take8)\ncollect(iter4_take8_not_red)",
"execution_count": 11,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 11,
"data": {
"text/plain": "5-element Array{Symbol,1}:\n :green\n :blue\n :green\n :blue\n :green"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "ac = Iterators.accumulate((x, y) -> x + (2y - 1), iter2_take5)\ncollect(ac)",
"execution_count": 12,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 12,
"data": {
"text/plain": "5-element Array{Int64,1}:\n 0\n 1\n 4\n 9\n 16"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "rev = Iterators.reverse(1:6)\ncollect(rev)",
"execution_count": 13,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 13,
"data": {
"text/plain": "6-element Array{Int64,1}:\n 6\n 5\n 4\n 3\n 2\n 1"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "using Printf\n\na = [\"abc$(@sprintf \"%04d\" k)\" for k in 0:10]\n@show a\niter = Iterators.partition(a, 4)\n@show length(iter)\ncollect(iter)",
"execution_count": 14,
"outputs": [
{
"output_type": "stream",
"text": "a = [\"abc0000\", \"abc0001\", \"abc0002\", \"abc0003\", \"abc0004\", \"abc0005\", \"abc0006\", \"abc0007\", \"abc0008\", \"abc0009\", \"abc0010\"]\nlength(iter) = 3\n",
"name": "stdout"
},
{
"output_type": "execute_result",
"execution_count": 14,
"data": {
"text/plain": "3-element Array{SubArray{String,1,Array{String,1},Tuple{UnitRange{Int64}},true},1}:\n [\"abc0000\", \"abc0001\", \"abc0002\", \"abc0003\"]\n [\"abc0004\", \"abc0005\", \"abc0006\", \"abc0007\"]\n [\"abc0008\", \"abc0009\", \"abc0010\"]"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "collect(Iterators.partition(collect(1:10), 4))",
"execution_count": 15,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 15,
"data": {
"text/plain": "3-element Array{SubArray{Int64,1,Array{Int64,1},Tuple{UnitRange{Int64}},true},1}:\n [1, 2, 3, 4]\n [5, 6, 7, 8]\n [9, 10]"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "collect(Iterators.partition(1:10, 4))",
"execution_count": 16,
"outputs": [
{
"output_type": "execute_result",
"execution_count": 16,
"data": {
"text/plain": "3-element Array{UnitRange{Int64},1}:\n 1:4\n 5:8\n 9:10"
},
"metadata": {}
}
]
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "for (d, files) in enumerate(Iterators.partition(a, 4))\n outputfile = @sprintf \"output%04d\" d\n @show files\n @show outputfile\n @show `foo $files -o $outputfile`\n println()\nend",
"execution_count": 17,
"outputs": [
{
"output_type": "stream",
"text": "files = [\"abc0000\", \"abc0001\", \"abc0002\", \"abc0003\"]\noutputfile = \"output0001\"\n`foo $files -o $outputfile` = `foo abc0000 abc0001 abc0002 abc0003 -o output0001`\n\nfiles = [\"abc0004\", \"abc0005\", \"abc0006\", \"abc0007\"]\noutputfile = \"output0002\"\n`foo $files -o $outputfile` = `foo abc0004 abc0005 abc0006 abc0007 -o output0002`\n\nfiles = [\"abc0008\", \"abc0009\", \"abc0010\"]\noutputfile = \"output0003\"\n`foo $files -o $outputfile` = `foo abc0008 abc0009 abc0010 -o output0003`\n\n",
"name": "stdout"
}
]
},
{
"metadata": {},
"cell_type": "markdown",
"source": "See alsp https://julialang.org/blog/2013/04/put-this-in-your-pipe/"
},
{
"metadata": {
"trusted": true
},
"cell_type": "code",
"source": "",
"execution_count": null,
"outputs": []
}
],
"metadata": {
"kernelspec": {
"name": "julia-1.4",
"display_name": "Julia 1.4.2",
"language": "julia"
},
"toc": {
"nav_menu": {},
"number_sections": true,
"sideBar": true,
"skip_h1_title": false,
"base_numbering": 1,
"title_cell": "Table of Contents",
"title_sidebar": "Contents",
"toc_cell": false,
"toc_position": {},
"toc_section_display": true,
"toc_window_display": false
},
"language_info": {
"file_extension": ".jl",
"name": "julia",
"mimetype": "application/julia",
"version": "1.4.2"
},
"@webio": {
"lastKernelId": null,
"lastCommId": null
},
"gist": {
"id": "2bdf5999454c176ffb27d85e3e9d8b7b",
"data": {
"description": "Iterators",
"public": true
}
},
"_draft": {
"nbviewer_url": "https://gist.github.com/2bdf5999454c176ffb27d85e3e9d8b7b"
}
},
"nbformat": 4,
"nbformat_minor": 4
}
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