January 2020
Intermediate to advanced
584 pages
7h 18m
Japanese
Content preview from Rクックブック 第2版
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8章確率
確率論は統計学の基本です。Rには確率、確率分布、確率変数を扱うための仕組みがいくつも用意されています。本章のレシピでは、分位数から確率を求める方法、確率から分位数を求める方法、分布から取り出した確率変数の生成方法、分布のプロット方法などを紹介します。
分布の名前
Rではすべての確率分布に省略名があります。その分布に関連する関数を特定するのにこの名前を使います。例えば、正規分布の名前は「norm」で、表8-1の関数名のベースになっています。
表8-1 正規分布関数
| 関数 | 目的 |
|---|---|
dnorm | 正規密度関数 |
pnorm | 正規分布関数 |
qnorm | 正規分布の分位関数†1 |
rnorm | 正規乱数 |
[†1] 訳注：分布関数の逆。
表8-2に一般的な離散分布を、表8-3に一般的な連続分布をまとめました。
表8-2 一般的な離散分布
| 離散分布 | R上の名前 | パラメータ |
|---|---|---|
| 二項分布 | binom | n＝試行回数、p＝1回の試行での成功の確率 |
| 幾何分布 | geom | p＝1回の試行での成功の確率 |
| 超幾何分布 | hyper | m＝壺（urn）内の白玉の数、n＝壺内の黒玉の数、k＝壺から取り出した玉の数 |
| 負の二項（NegBinomial）分布 | nbinom | size＝成功試行の数、prob＝成功試行の確率またはmu＝平均 |
| ポアソン分布 | pois | lambda＝平均 |
表8-3 一般的な連続分布
| 連続分布 | R上の名前 | パラメータ |
|---|---|---|
| ベータ分布 | beta | shape1、shape2 |
| コーシー分布 | cauchy | location、scale |
| カイ二乗（Chisquare）分布 | chisq | df＝自由度 |
| 指数分布 | exp | rate |
| F分布 | f | df1とdf2＝自由度 |
| ガンマ分布 | gamma | rateまたはscale |
| 対数正規（Lognormal）分布 | lnorm | meanlog ... |
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.