How to find unique words given a list of words in R

Question

I have a list of words

a = c("when","to","use","each","effect","","recognizing","each","effect","?",":")
a
[1] "when"        "to"          "use"         "each"       
[5] "effect"      ""            "recognizing" "each"       
[9] "effect"      "?"           ":"

This list could have contained thousands of words. How can I effectively find out the unique words, i.e. "when" "to" "use" "each" "effect" "recognizing"?

I am trying to avoid for loops whenever possible.

Thanks

Have you tried a bit of a search? Unique entries are given by `unique`, surprisingly. — tonytonov, Feb 07 '14 at 07:36
Add all to a [KeySet][1] which will take care [1]: http://stackoverflow.com/questions/8962459/java-collections-keyset-vs-entryset-in-map — Raghunandan Krishnamurthy, Feb 07 '14 at 07:42
Sorry for asking such a dumb question. I am a new comer to the R game. I didn't know "unique" exists. — wen, Feb 07 '14 at 08:34

score 2 · Accepted Answer · answered Feb 07 '14 at 07:35

2

unique(a)

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table(a)

answered Feb 07 '14 at 07:35

JeremyS

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Thanks, I was searching online for like a hour. Didn't know it's this easy! – wen Feb 07 '14 at 08:33
First thing to try is type `?unique` (or whatever) into R, if that comes up empty then `??unique`, if that comes up empty then web search. – JeremyS Feb 07 '14 at 08:36

score -1 · Answer 2 · answered Feb 07 '14 at 07:38

-1

You can use a hashmap to maintain the list instead of using an array. It would automatically maintain the uniqueness of your data.

answered Feb 07 '14 at 07:38

Saket

124
9

How to find unique words given a list of words in R

2 Answers2