October 2017
Intermediate to advanced
480 pages
9h 49m
Japanese
Content preview from Rではじめるデータサイエンス
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
17.3
for
ループのバリエーション
283
out <- vector("list", length(means))
for (i in seq_along(means)) {
n <- sample(100, 1)
out[[i]] <- rnorm(n, means[[i]])
}
str(out)
#> List of 3
#> $ : num [1:83] 0.367 1.13 -0.941 0.218 1.415 ...
#> $ : num [1:21] -0.485 -0.425 2.937 1.688 1.324 ...
#> $ : num [1:40] 2.34 1.59 2.93 3.84 1.3 ...
str(unlist(out))
#> num [1:144] 0.367 1.13 -0.941 0.218 1.415 ...
ここでは、ベクトルのリストを1 つのベクトルにするために
unlist()
を使いました。より安全な
のは
purrr::flatten_dbl()
を使うことです。これは、入力が
double
のリストでないとエラーを投
げます。
このパターンは他の場合でも生じます。
●
長い文字列を生成する場合。繰り返しのたびに前の文字列に
paste()
するのではなく、出力を文
字ベクトルに保存しておき、
paste(output, collapse = "")
でベクトルの要素を連結して文字
列にする。
●
大きなデータフレームを生成する場合。繰り返しのたびに
rbind()
で逐次作 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.