August 2015
Intermediate to advanced
272 pages
5h 46m
Japanese
Content preview from Think Stats 第2版 ―プログラマのための統計入門
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35
35
3.2 PMF をプロットする
となく、コピーを作成してそれを変更できます。
本節の記法は不統一に見えたかもしれませんが、
Pmf
はクラスの名前、
pmf
はクラ
スのインスタンス、
PMF
は確率質量関数という数学的概念をそれぞれ表します。
3.2
PMF
をプロットする
thinkplot
には、
Pmf
をプロットする方法が
2
つあります。
• Pmf
を棒グラフとして描画するには、
thinkplot.Hist
を使う。
Pmf
中の値
の個数が少ない場合、棒グラフが最も向いている。
• Pmf
をステップ関数として描画するには、
thinkplot.Pmf
を使う。これは、
Pmf
に多くの値がありかつ滑らかな場合に向いている。この関数は
Hist
オ
ブジェクトにも使える。
さらに、シーケンス型の値を取ってヒストグラムを計算する
hist
という関数を
pyplot
が提供しています。
Hist
オブジェクトを使うので、私は普通
pyplot.hist
は
使いません。
図
3-1
は第一子と第二子以降との妊娠期間の
PMF
を棒グラフ（左）とステップ関
数（右）で描画したものです。
ヒストグラムの代わりに
PMF
をプロットすることにより、
2
つの分布を、標本サ
イズの違いで紛らわしくなることなく、比較できます。この図からは、第一子が予定
日（第
39
週）どおりに出産する確率が第二子以降に比べて少し低く、少し遅れる場
合（第
41
〜
42
週）が多いようです。
図
3-1
を生成するコードは次のようになります。
thinkplot.PrePlot(2, cols=2)
thinkplot.Hist(first_pmf, ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.