Cumulative standard deviation: Difference between revisions
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ReeceGoding (talk | contribs) (→{{header|R}}: Solution that gives every result so far, rather than just the final result.) |
ReeceGoding (talk | contribs) (→{{header|R}}: Added what I believe to be a true stateful solution. I'm not well-informed about the terminology. Hopefully I've not accidentally made a generator.) |
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<pre>> cumSd(c(2, 4, 4, 4, 5, 5, 7, 9)) |
<pre>> cumSd(c(2, 4, 4, 4, 5, 5, 7, 9)) |
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[1] 0.0000000 1.0000000 0.9428090 0.8660254 0.9797959 1.0000000 1.3997084 2.0000000</pre> |
[1] 0.0000000 1.0000000 0.9428090 0.8660254 0.9797959 1.0000000 1.3997084 2.0000000</pre> |
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===Stateful SD=== |
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If we want a function that remembers and uses the previous inputs, letting us be very strict about the "one at a time" requirement, then we can lift biasedSd from the previous solution and make good use of the distinction between R's <- and <<- methods of assignment. |
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<lang r>cumSDStateful<-function() |
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{ |
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data<-numeric(0) |
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function(oneNumber) |
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{ |
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data<<-c(data,oneNumber) |
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biasedSd(data) |
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} |
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} |
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state<-cumSDStateful()</lang> |
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{{out}} |
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<pre>> state(2);state(4);state(4);state(4);state(5);state(5);state(7);state(9) |
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[1] 0 |
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[1] 1 |
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[1] 0.942809 |
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[1] 0.8660254 |
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[1] 0.9797959 |
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[1] 1 |
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[1] 1.399708 |
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[1] 2</pre> |
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=={{header|Racket}}== |
=={{header|Racket}}== |
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