あれまぁ～ - スナックelve 本店

皆さんこんばんは。スマホで読みづらくムダに長く誰も読んでない疑惑が出るプログラミング記事の時間ですよ。
リフレクションだかなんだかでハマってめちゃ時間かかりましたが、ifで分岐するのと配列にアクセスするのとどっちが速いのかな検証です。

100配列
8配列
3配列
if文if入れ子
if文ifelseあり

とかを作って1000回×5回で平均時間取ってみました
ソースは下に載せとく。バグってると思うので注意。

java

何故か配列100個用意したのが一番遅かった。コンパイルするから？（関係なさげｗ）素直にelseif使うのが一番早かったです。

elseIfBlockBの処理時間	59.4
elseIfBlockAの処理時間	62
testArray3の処理時間	68.4
testArray7の処理時間	71.2
elseIfSingleの処理時間	71.8
ifSingleの処理時間	75.4
ifBlockの処理時間	79
testArray100の処理時間	121.6

python

これは配列3つにアクセスするのが早かったけど、三項条件式がifなのでうーむ、と言う感じ。配列組が頑張ってる。ビット演算するとひどく大変なのかもしれない(；´Д｀)

testProcess_array3	0.213850307
testProcess_array100	0.23054862
testProcess_ifSingleB	0.23359828
testProcess_ifSingleA	0.240833712
testProcess_array7	0.263782549

エクセルのマクロ（vba）

インタプリタ？　100配列がめっちゃ作りにくいというかどう頑張っても配列を引数にできなくてｗ　ワークシートから直接値とるようにしました。Iif、実は速いのか？！

array3	0.850260417
testIf	0.858072917
testElseIfBlock	0.861979167
testIfBlock	0.864583333
array7	0.899739583
array100	0.95703125

ソース

testArray7が実は100入れたらバグってるんだが止まらなかったなぁ・・・。

class test {
 
    public String testArray100(int x) {
        String re[] = { "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C",
                "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "C",
                "C", "C", "C", "C", "C", "C", "C", "C", "C", "C", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B",
                "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "A", "A",
                "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A" };
        return re[x];
    }

    public String testArray7(int x) {
        String re[] = { "C", "", "B", "", "", "", "A" };
        int a = (x / 80) << 2 | (x / 50) << 1;
        return re[a];
    }

    public String testArray3(int x) {
        String re[] = { "C", "B", "A" };
        int a = x >= 80 ? 2 : x >= 50 ? 1 : 0;
        return re[a];
    }

    public String ifSingle(int x) {
        if (x >= 80)
            return "A";
        if (x >= 50)
            return "B";
        return "C";
    }

    public String elseIfSingle(int x) {
        if (x >= 80)
            return "A";
        else if (x >= 50)
            return "B";
        else
            return "C";
    }

    public String ifBlock(int x) {
        if (x >= 80) {
            return "A";
        }
        if (x >= 50) {
            return "B";
        }
        return "C";
    }

    public String elseIfBlockA(int x) {
        if (x >= 80) {
            return "A";
        } else {
            if (x >= 50) {
                return "B";
            } else {
                return "C";
            }
        }
    }

    public String elseIfBlockB(int x) {
        if (x >= 80) {
            return "A";
        } else if (x >= 50) {
            return "B";
        } else {
            return "C";
        }
    }

わからなすぎて分からない呼び出し部分

import java.util.Random;
import java.lang.reflect.Method;

public class App {
    public static void main(String[] args) throws Exception {
        String fName[] = { "testArray100", "testArray7", "testArray3", "ifSingle", "elseIfSingle", "ifBlock",
                "elseIfBlockA", "elseIfBlockB" };
        // 文字列をクラスオブジェクトに変換する
        String strClass = "test";
        Class<?> c = Class.forName(strClass);

        /* クラスのインスタンス化と実行 */
        // インスタンス化
        Object obj = c.getDeclaredConstructor().newInstance();
        // メソッドの定義と実行
        String[] str=new String[8];
        for (int i = 0; i < 8; i++) {
            Method m2 = c.getMethod(fName[i], int.class);
            long startTime = System.currentTimeMillis();
            for (int j = 0; j < 1000; j++) {
                Random random = new Random();
                int x = random.nextInt(101);
                System.out.print(x + "は" + m2.invoke(obj, x) + "です");
            }
            str[i] = fName[i] + "の処理時間：" + (System.currentTimeMillis() - startTime) + " ms";
        }
        System.out.println("");
        for (int i = 0; i < 8; i++) {
            System.out.println(str[i]);
        }
    }
}

一番スッキリかけた感じ

from ast import Num
import random
from time import time


def testProcess_array100(x):
    re = ["not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB",
          "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB",
          "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB",
          "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB",
          "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB", "not AB",
          "not AB", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B",
          "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "B", "A", "A", "A", "A", "A", "A", "A", "A", "A",
          "A", "A", "A", "A", "A", "A", "A", "A", "A", "A", "A"]
    return re[x]


def testProcess_array7(x):
    re = ["not AB", "", "", "B", "", "", "A"]
    a = ((x//80) << 2) | ((x//50) << 1)
    return re[a]


def testProcess_array3(x):
    re = ["not AB", "B", "A"]
    a = 2 if x >= 80 else 1 if x >= 50 else 0
    return re[a]


def testProcess_ifSingleA(x):
    re = ["not AB", "B", "A"]
    if x >= 80:
        a = 2
    elif x >= 50:
        a = 1
    else:
        a = 0
    return re[a]


def testProcess_ifSingleB(x):
    re = ["not AB", "B", "A"]
    if x >= 80:
        a = 2
    else:
        if x >= 50:
            a = 1
        else:
            a = 0
    return re[a]


proc_time = []

funcs = {"testProcess_array100", "testProcess_array7",
         "testProcess_array3", "testProcess_ifSingleA", "testProcess_ifSingleB"}
for index,func in enumerate(funcs):
    start1 = time()
    for i in range(1000):
        x = random.randint(0, 100)
        re = locals()[func](x)
        print(str(x) + "は" + re + "だよ")
    proc_time.insert(index, func + ": " + str(time() - start1))
print(proc_time)

runでどう頑張ってもfunction呼べなくて断念。

Option Explicit

Sub main()
Dim i As Integer
Dim r As Integer: r = 1
Dim startTime As Double
Dim j As Integer
For j = 0 To 5
    Sheet3.Cells(r, 4) = "array100"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (array100(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
    Sheet3.Cells(r, 4) = "array7"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (array7(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
    Sheet3.Cells(r, 4) = "array3"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (array3(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
    Sheet3.Cells(r, 4) = "testIf"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (testIf(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
    Sheet3.Cells(r, 4) = "testIfBlock"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (testIfBlock(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
    Sheet3.Cells(r, 4) = "testElseIfBlock"
    startTime = Timer
    For i = 0 To 1000
        Debug.Print (testElseIfBlock(Int((100 - 0 + 1) * Rnd + 0)))
    Next
    Sheet3.Cells(r, 5) = Timer - startTime
    r = r + 1
Next
End Sub
Function array100(x As Integer) As String
    Dim ret As String: ret = Sheet3.Cells(x + 1, 1)
    array100 = ret
End Function
Function array7(x As Integer) As String
    Dim re(8) As String
    re(0) = "C"
    re(2) = "B"
    re(6) = "A"
    re(8) = "A"
    Dim a As Integer
    a = ((x \ 80) * (2 ^ 2)) + ((x \ 50) * (2 ^ 1))
    array7 = re(a)
End Function
Function array3(x As Integer) As String
    Dim re(3) As String
    re(0) = "C"
    re(1) = "B"
    re(2) = "A"
    Dim a As Integer
    a = IIf(x >= 80, 2, IIf(x >= 50, 1, 0))
    array3 = re(a)
End Function
Function testIf(x As Integer) As String
    Dim re As String
    If x >= 80 Then re = "A" Else If x >= 50 Then re = "B" Else re = "C"
    testIf = re
End Function
Function testIfBlock(x As Integer) As String
    Dim re As String
    If x >= 80 Then
        re = "A"
    Else
        If x >= 50 Then
            re = "B"
        Else
            re = "C"
        End If
    End If
    testIfBlock = re
End Function
Function testElseIfBlock(x As Integer) As String
    Dim re As String
    If x >= 80 Then
        re = "A"
    ElseIf x >= 50 Then
        re = "B"
    Else
        re = "C"
    End If
    testElseIfBlock = re
End Function

参考