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
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11.3
正規表現でパターンマッチ
177
\d
や
\s
を含む正規表現を作るには、文字列で
\
をエスケープする必要があることを忘れないよう
にします。
複数の候補パターンから選ぶには候補指定（
|
）を使います。例えば、
abc|d..f
は
"abc"
または
"deaf"
のいずれかとマッチします。
|
の演算順位は低いので、
abc|xyz
は
abc
または
xyz
とマッチし
ますが
abcyz
や
abxyz
とはマッチしません。数式の場合同様、混乱を避けるには括弧を使って意図を
明確にします。
str_view(c("grey", "gray"), "gr(e|a)y")
1. 次の語を探す正規表現を作りなさい。
a. 母音で始まる。
b. 子音からなる（ヒント：母音以外とマッチする）。
c.
ed
で終わるが、
eed
では終わらない。
d.
ing
または
ize
で終わる。
2. 「 c の後以外は e の前に i 」という規則を実際に検証しなさい。
3. 「q」の後には常に「u」が続くか。
4. アメリカ英語ではなくイギリス英語で書かれている英単語にマッチする正規表現を書きなさい。
5. 自分の国で普通の書き方の電話番号の正規表現を作りなさい。
11.3.4
繰り返し
次のステップでは、パターンマッチを何回繰り返すかを制御します。
正規表現 意味
?
0か1
+
1以上
*
0以上
x <- "1888 is the longest year in Roman numerals: MDCCCLXXXVIII"
str_view(x, "CC?")
str_view(x, ...
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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.