[R] questions hash functions

Jeff Newmiller jdnewmil at dcn.davis.CA.us
Mon Feb 18 05:32:26 CET 2013


I cannot imagine why you think this is the appropriate place to pose such a question. It certainly has nothing to do with R (which would be appropriate), and it does look like homework (which is identified as NOT appropriate in the Posting Guide for this mailing list).
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Sent from my phone. Please excuse my brevity.

"Tania Patiño" <taniuxpc at gmail.com> wrote:

>Hello R, could you explain to me how to resolve this question:
>
>If this is a matrix:
>
>Element S1 S2 S3 S4
>     0        0    1  0    1
>     1        0    1  0    0
>     2        1    0  0    1
>     3        0    0  1    0
>     4        0    0  1    1
>     5        1    0  0    0
>
>
>1.  How is possible to ompute the minhash signature for each column if
>we use the following
>three hash functions: h1(x) = 2x + 1 mod 6; h2(x) = 3x + 2 mod 6;
>h3(x) = 5x + 2 mod 6.
>
>2. Which of these hash functions are true permutations?
>
>3.How close are the estimated Jaccard similarities for the six pairs of
>columns
>to the true Jaccard similarities?
>
>Thank you!
>
>Tania
>
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