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gams:compute_the_median_of_a_parameter_s_values

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 gams:compute_the_median_of_a_parameter_s_values [2009/05/29 12:52]support created — (current) 2020/12/10 15:36 Atharv Bhosekar removed2009/05/29 12:52 support created Next revision Previous revision 2020/12/10 15:36 Atharv Bhosekar removed2009/05/29 12:52 support created Line 1: Line 1: - ====== How do I compute the median of a parameter'​s values? ====== - The code fragment below  was contributed by Tom Rutherford to the[[http://​www.gams.com/​maillist/​gams_l.htm|GAMS User List]], an example for multidimensional data is available on his web site [[http://​www.mpsge.org/​mdrank.htm|mpsge.org]]. - - <​code>​ - \$title ​ Finding the Median of a Distribution in GAMS - - set     ​i ​      ​Individuals /i1*i1000/; - alias (i,j); - parameter ​      ​income(i) ​      ​Personal income, - rank(i) ​        ​Income rank, - median ​         Median income; - *       Make it random for the purpose of illustration:​ - income(i) = uniform(0,​1);​ - *       This is ugly and slow, but it works: - rank(i) = sum(j\$(income(j) gt income(i)), 1) + 1; - - * In this example there will be no ties, there could be a tie in an arbitrary - * application. ​ Just to be safe,  divide through by the number of - * median individuals:​ - - median = sum(i\$(rank(i) eq round(card(i)/​2)),​ income(i)) - / sum(i\$(rank(i) eq round(card(i)/​2)),​ 1); - - display median; -