performance - How do I convert this nested foreach to linq C# -


when tried convert nested foreach linq, i'm unable it. have tried of several ways nothing. didn't result these foreach

foreach (string field in extractorresults.keys) {     if (fileresults.containskey(field)) {         foreach (extractionresult exresult in extractorresults[field]) {             fileresults[field].add(exresult);         }     } else         fileresults.add(field, extractorresults[field]);     } }

seems trying 'merge' 2 dictionaries:

fileresults = fileresults.concat(extractorresults)                  .groupby(kvp => kvp.key)                  .todictionary(g => g.key, g => g.selectmany(kvp => kvp.value).tolist());

explanation:

  1. get keyvaluepairs both dictionaries
  2. group keyvaluepairs keys
  3. create new dictionary contain entry each group - same key , list of values selected grouped keyvaluepairs. can add distinct() call after selecting values if don't want duplications in result. though original foreach-based logic produces duplicates.

step step (i'll use json format show data flow):

assume have 2 dictionaries following data (actual data types not matter here):

  fileresults = [      { key:"a", value: [1,2] },      { key: "b", value: [5] }   ];    extractorresults = [      { key:"c", value: [7] },        { key: "b", value: [3,4] }   ];

after concatenating these dictionaries single sequence of key value pairs

 [     { key:"a", value: [1,2] },      { key: "b", value: [5] },     { key:"c", value: [7] },       { key: "b", value: [3,4] }  ]

next goes grouping:

 [     { key: "a", items: [ { key:"a", value: [1,2] } ] },     { key: "b", items: [ { key: "b", value: [5] }, { key: "b", value: [3,4] },     { key: "c", items: [ { key:"c", value: [7] } ]  ]

and create new dictionary entries each group above:

 [     { key: "a", value: [1, 2] },     { key: "b", value: [5, 3, 4] },     { key: "c", value: [7] }  ]

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