{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Rcpp入門 その2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "「オリジナルのR」、「RcppArmadillo」、「RcppEigen」で処理速度の比較をしてみたいと思います。\n",
    "\n",
    "「RcppArmadillo」、「RcppEigen」を使うのは、恐らく以下のような時だと思います。\n",
    "\n",
    "* forループを多用しなくてはいけない時\n",
    "* ライブラリ固有の関数を使いたい時\n",
    "\n",
    "[Rcpp入門](Rcpp_Getting_Started.ipynb)の関数を、1固定ではなく、行番号+列番号とした関数を作成して比較します。\n",
    "\n",
    "※ バージョンによっては正常に動作しない場合があります。私が試した環境は、\n",
    "\n",
    "* R version 3.4.1\n",
    "* Rcpp 0.12.12\n",
    "* RcppArmadillo 0.7.960.1.2\n",
    "* RcppEigen 0.3.3.3.0"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Rで作成した関数"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "PlusIJ_R <- function(src)\n",
    "{\n",
    "    num_row <- nrow(src)\n",
    "    num_col <- ncol(src)\n",
    "    \n",
    "    for(r in 1:num_row)\n",
    "    {\n",
    "        for(c in 1:num_col)\n",
    "        {\n",
    "            src[r, c] = src[r, c] + r + c\n",
    "        }\n",
    "    }\n",
    "    \n",
    "    return(src)\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## RcppArmadilloで作成した関数"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1] '0.12.12'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "[1] '0.7.960.1.2'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# パッケージの読込み\n",
    "library(Rcpp)\n",
    "library(RcppArmadillo)\n",
    "\n",
    "# パッケージのバージョンの確認\n",
    "packageVersion(\"Rcpp\")\n",
    "packageVersion(\"RcppArmadillo\")\n",
    "\n",
    "# C+11にてコンパイルします\n",
    "Sys.setenv(\"PKG_CXXFLAGS\"=\"-std=c++11\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "# C++のコード\n",
    "code <- '\n",
    "arma::mat PlusIJ_Arma(arma::mat src)\n",
    "{\n",
    "    int num_row = src.n_rows;\n",
    "    int num_col = src.n_cols;\n",
    "    \n",
    "    for(int r = 0; r < num_row; r++)\n",
    "    {\n",
    "        for(int c = 0; c < num_col; c++)\n",
    "        {\n",
    "            src(r, c) = src(r, c) + r + 1 + c + 1;\n",
    "        }\n",
    "    }\n",
    "\n",
    "    return src;\n",
    "}\n",
    "'\n",
    "\n",
    "# コンパイルとリンクを行います（少し時間がかかります）\n",
    "cppPlusIJ_Arma <- cppFunction(code, depends=\"RcppArmadillo\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## RcppEigenで作成した関数"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "\n",
      "Attaching package: 'RcppEigen'\n",
      "\n",
      "The following objects are masked from 'package:RcppArmadillo':\n",
      "\n",
      "    fastLm, fastLmPure\n",
      "\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[1] '0.12.12'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "[1] '0.3.3.3.0'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# パッケージの読込み\n",
    "library(Rcpp)\n",
    "library(RcppEigen)\n",
    "\n",
    "# パッケージのバージョンの確認\n",
    "packageVersion(\"Rcpp\")\n",
    "packageVersion(\"RcppEigen\")\n",
    "\n",
    "# C+11にてコンパイルします\n",
    "Sys.setenv(\"PKG_CXXFLAGS\"=\"-std=c++11\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# C++のコード\n",
    "code <- '\n",
    "Eigen::MatrixXd PlusIJ_Eigen(Eigen::MatrixXd src)\n",
    "{\n",
    "    int num_row = src.rows();\n",
    "    int num_col = src.cols();\n",
    "    \n",
    "    for(int r = 0; r < num_row; r++)\n",
    "    {\n",
    "        for(int c = 0; c < num_col; c++)\n",
    "        {\n",
    "            src(r, c) = src(r, c) + r + 1 + c + 1;\n",
    "        }\n",
    "    }\n",
    "\n",
    "    return src;\n",
    "}\n",
    "'\n",
    "\n",
    "# コンパイルとリンクを行います（少し時間がかかります）\n",
    "cppPlusIJ_Eigen <- cppFunction(code, depends=\"RcppEigen\", includes=c(\"#include <RcppEigen.h>\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 比較"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "元データを作成します。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "src <- matrix(1:100000000, nrow=10000)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Rで作成した関数**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "   user  system elapsed \n",
      "  11.17    0.05   11.23 \n"
     ]
    }
   ],
   "source": [
    "t <- proc.time()\n",
    "\n",
    "dst_r <- PlusIJ_R(src)\n",
    "\n",
    "print(proc.time() - t)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**RcppArmadilloで作成した関数**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "   user  system elapsed \n",
      "   1.92    0.48    2.40 \n"
     ]
    }
   ],
   "source": [
    "t <- proc.time()\n",
    "\n",
    "dst_arma <- cppPlusIJ_Arma(src)\n",
    "\n",
    "print(proc.time() - t)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**RcppEigenで作成した関数**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "   user  system elapsed \n",
      "   1.82    0.51    2.34 \n"
     ]
    }
   ],
   "source": [
    "t <- proc.time()\n",
    "\n",
    "dst_eigen <- cppPlusIJ_Eigen(src)\n",
    "\n",
    "print(proc.time() - t)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**結果のチェック**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1] \"RcppArmadilloで作成した関数チェック\"\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "TRUE"
      ],
      "text/latex": [
       "TRUE"
      ],
      "text/markdown": [
       "TRUE"
      ],
      "text/plain": [
       "[1] TRUE"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1] \"RcppEigenで作成した関数チェック\"\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "TRUE"
      ],
      "text/latex": [
       "TRUE"
      ],
      "text/markdown": [
       "TRUE"
      ],
      "text/plain": [
       "[1] TRUE"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "print(\"RcppArmadilloで作成した関数チェック\")\n",
    "all(dst_r == dst_arma)\n",
    "print(\"RcppEigenで作成した関数チェック\")\n",
    "all(dst_r == dst_eigen)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "今回の結果としては、以下の順位になりました。\n",
    "\n",
    "1. 「RcppArmadillo」 ≒ 「RcppEigen」\n",
    "1. 「オリジナルのR」\n",
    "\n",
    "forループを多用するコードになる場合は積極的に、「RcppArmadillo」や「RcppEigen」を使うべきだと思いました。\n",
    "\n",
    "「RcppArmadillo」と「RcppEigen」のどちらを利用するかは、悩みどころです。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "----\n",
    "[ホームへ](https://waku-take-a.github.io/index.html)  \n",
    "[↑Rの記事Topへ](https://waku-take-a.github.io/R.html) \n",
    "\n",
    "※  \n",
    "上記のipynbファイル等は、[こちらに](https://github.com/WAKU-TAKE-A/RTips)あります。  \n",
    "解凍後、`The jupyter notebook`にアップロードすれば、ローカルな環境で実行することも、編集することもできます。\n",
    "\n",
    "<(_ _)>"
   ]
  }
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