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sub と gsub(2)

Regular expressions are a typical concept that you'll learn by doing and by seeing other examples. Before you rack your brains over the regular expression in this exercise, have a look at the new things that will be used:

  • .*: A usual suspect! It can be read as "any character that is matched zero or more times".
  • \\s: Match a space. The "s" is normally a character, escaping it (\\) makes it a metacharacter.
  • [0-9]+: Match the numbers 0 to 9, at least once (+).
  • ([0-9]+): The parentheses are used to make parts of the matching string available to define the replacement. The \\1 in the replacement argument of sub() gets set to the string that is captured by the regular expression [0-9]+.
awards <- c("Won 1 Oscar.",
  "Won 1 Oscar. Another 9 wins & 24 nominations.",
  "1 win and 2 nominations.",
  "2 wins & 3 nominations.",
  "Nominated for 2 Golden Globes. 1 more win & 2 nominations.",
  "4 wins & 1 nomination.")

sub(".*\\s([0-9]+)\\snomination.*$", "\\1", awards)

What does this code chunk return? awards is already defined in the workspace so you can start playing in the console straight away.

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