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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170
11
章
stringr
による文字列
閉じの引用符を忘れるとRStudioでは
+
という継続文字がプロンプトされます。
> "This is a string without a closing quote
+
+
+ HELP I'M STUCK
このような場合にはEscを押してやり直します。
文字列に引用符を1 文字含めるには、
\
を使って「エスケープ」します。
double_quote <- "\"" #
または
'"'
single_quote <- '\'' #
または
"'"
つまり、バックスラッシュを含めたければ2 個、
\\
と書きます。
文字列の出力は、エスケープが書かれていることからもわかるように、文字列そのものとは違うこ
とに注意。文字列の中身そのものを調べるには
writeLines()
を使います。
x <- c("\"", "\\")
x
#> [1] "\"" "\\"
writeLines(x)
#> "
#> \
特殊文字は他にもいくつかあります。よく使われるのが、改行の
"\n"
とタブの
"\t"
です。
?'"'
ま
たは
?"'"
と入力してヘルプですべての特殊文字の一覧を表示できます。
"\u00b5"
のような文字列も
見かけるでしょうが、これは非英語文字をあらゆるプラットフォームで書くための方式です。
x <- "\u00b5"
x
#> [1] "µ"
複数の文字列は、
c()
で作る文字列ベクトルに格納することが多いでしょう。
c("one", "two", "three")
#> [1] "one" "two" ...
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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.