Arrays and Hashes processing :pls help

Discussion in 'Ruby' started by Jags Rao, Feb 12, 2009.

  1. Jags Rao

    Jags Rao Guest

    hi friends

    i have a long array with structure like this

    [["377", "838"],
    ["377", "990"],
    ["377", "991"],
    ["377", "992"],
    ["378", "840"],
    ["378", "841"],
    ["378", "842"],
    ["378", "843"],
    ["378", "844"]]

    how can i convert it in one line to

    [["377", "838 990 991 992"],
    ["378", "840 841 842 843 844"]]

    if thats diificult is the below array processable in one line

    [{"prefix"=>"838", "scf_id"=>"377"},
    {"prefix"=>"990", "scf_id"=>"377"},
    {"prefix"=>"991", "scf_id"=>"377"},
    {"prefix"=>"992", "scf_id"=>"377"},
    {"prefix"=>"840", "scf_id"=>"378"},
    {"prefix"=>"841", "scf_id"=>"378"},
    {"prefix"=>"842", "scf_id"=>"378"},
    {"prefix"=>"843", "scf_id"=>"378"},
    {"prefix"=>"844", "scf_id"=>"378"}]

    in this form

    [{"prefix"=>"838 990 991 992", "scf_id"=>"377"},
    {"prefix"=>"840 841 842 843 844", "scf_id"=>"378"}]

    pls help
    Jags
     
    Jags Rao, Feb 12, 2009
    #1
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  2. I don't understand the need for one line, but.... Also, why an array of
    hashes? why not a hash?

    if your array of hashes is referenced by h, then:
    out = h.inject({}) {|s,v| x=s[v["scf_id"]] || ""; s[v["scf_id"]]="#{x}
    #{v["prefix"]}".trim;s}

    that (above) gives you a hash with distinct values of scf_id referencing
    prefixes. That said, you can do the following if you *must* have an
    array:
    out = (h.inject({}) {|s,v| x=s[v["scf_id"]] || ""; s[v["scf_id"]]="#{x}
    #{v["prefix"]}".trim;s}).inject([]){|s,v|
    s<<{"scf_id"=>v[0],"prefix"=>v[1]};s}

    It's ugly. Not maintainable.

    Why the need for one line?
     
    Matt Williams, Feb 12, 2009
    #2
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  3. Why in a single line?

    Cheers

    robert
     
    Robert Klemme, Feb 12, 2009
    #3
  4. Jags Rao

    w_a_x_man Guest

    a = [["377", "838"],
    ["377", "990"],
    ["377", "991"],
    ["377", "992"],
    ["378", "840"],
    ["378", "841"],
    ["378", "842"],
    ["378", "843"],
    ["378", "844"]]
    h=Hash.new{[]};a.each{|x,y|h[x]+=[y]};h.map{|x,y|[x,y.join(" ")]}
    ==>[["377", "838 990 991 992"], ["378", "840 841 842 843 844"]]
     
    w_a_x_man, Feb 12, 2009
    #4
  5. Jags Rao

    Jags Rao Guest

    hi guys
    thank u so much for the help.
    no issues with a multi line solution also

    -Jags
     
    Jags Rao, Feb 13, 2009
    #5
  6. original_array = [["377", "838"],
    ["377", "990"],
    ["377", "991"],
    ["377", "992"],
    ["378", "840"],
    ["378", "841"],
    ["378", "842"],
    ["378", "843"],
    ["378", "844"]]

    new_array = original_array.group_by {|x| x[0]}.map {|k,v| [k, v.join(" ")]}
     
    Christopher Dicely, Feb 13, 2009
    #6
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