Data commit

Task/Merge-and-aggregate-datasets/C-sharp/merge-and-aggregate-datasets.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Runtime.Serialization;
+
+public static class MergeAndAggregateDatasets
+{
+    public static void Main()
+    {
+        string patientsCsv = @"
+PATIENT_ID,LASTNAME
+1001,Hopper
+4004,Wirth
+3003,Kemeny
+2002,Gosling
+5005,Kurtz";
+
+        string visitsCsv = @"
+PATIENT_ID,VISIT_DATE,SCORE
+2002,2020-09-10,6.8
+1001,2020-09-17,5.5
+4004,2020-09-24,8.4
+2002,2020-10-08,
+1001,,6.6
+3003,2020-11-12,
+4004,2020-11-05,7.0
+1001,2020-11-19,5.3";
+
+        string format = "yyyy-MM-dd";
+        var formatProvider = new DateTimeFormat(format).FormatProvider;
+
+        var patients = ParseCsv(
+            patientsCsv.Split(Environment.NewLine, StringSplitOptions.RemoveEmptyEntries),
+            line => (PatientId: int.Parse(line[0]), LastName: line[1]));
+
+        var visits = ParseCsv(
+            visitsCsv.Split(Environment.NewLine, StringSplitOptions.RemoveEmptyEntries),
+            line => (
+                PatientId: int.Parse(line[0]),
+                VisitDate: DateTime.TryParse(line[1], formatProvider, DateTimeStyles.None, out var date) ? date : default(DateTime?),
+                Score: double.TryParse(line[2], out double score) ? score : default(double?)
+            )
+        );
+
+        var results =
+            patients.GroupJoin(visits,
+                p => p.PatientId,
+                v => v.PatientId,
+                (p, vs) => (
+                    p.PatientId,
+                    p.LastName,
+                    LastVisit: vs.Max(v => v.VisitDate),
+                    ScoreSum: vs.Sum(v => v.Score),
+                    ScoreAvg: vs.Average(v => v.Score)
+                )
+            ).OrderBy(r => r.PatientId);
+
+        Console.WriteLine("| PATIENT_ID | LASTNAME | LAST_VISIT | SCORE_SUM | SCORE_AVG |");
+        foreach (var r in results) {
+            Console.WriteLine($"| {r.PatientId,-10} | {r.LastName,-8} | {r.LastVisit?.ToString(format) ?? "",-10} | {r.ScoreSum,9} | {r.ScoreAvg,9} |");
+        }
+    }
+
+    private static IEnumerable<T> ParseCsv<T>(string[] contents, Func<string[], T> constructor)
+    {
+        for (int i = 1; i < contents.Length; i++) {
+            var line = contents[i].Split(',');
+            yield return constructor(line);
+        }
+    }
+
+}