Allow to create a series from tables or timetables

Author: Enric Sala

README.md

@@ -91,6 +91,12 @@ series = Series('weather') ...
     .fields('temperature', [10.5, 11.2, 9.7]) ...
     .time(datetime('now', 'TimeZone', 'local') - [0, 1, 2]);
 
+% Create a series from an existing timetable
+ttable = timetable(time, variables, etc);
+series = Series('weather') ...
+    .tags('city', 'helsinki', 'country', 'finland') ...
+    .import(ttable);
+
 % Save the series
 influxdb.writer() ...
     .append(series, etc) ...

influxdb-client/Series.m

@@ -54,6 +54,19 @@
             end
         end
 
+        % Import data from other structures
+        function obj = import(obj, data)
+            if istimetable(data) || istable(data)
+                insert = @(x) obj.field(x, data.(x));
+                cellfun(insert, data.Properties.VariableNames);
+                if istimetable(data)
+                    obj.time(data.Properties.RowTimes);
+                end
+            else
+                error('unsupported data structure');
+            end
+        end
+        
         % Format to Line Protocol
         function lines = toLine(obj, precision)
             time_length = length(obj.Time);

tests/SeriesTest.m

@@ -231,6 +231,31 @@ function time_supports_different_precisions(test)
                 test.verifyTrue(endsWith(line, exp));
             end
         end
+        
+        function imports_fields_from_table(test)
+            props = {test.Temperature, test.WindDirection};
+            names = {'temperature', 'wind_direction'};
+            data = table(props{:}, 'VariableNames', names);
+            s = Series('weather') ...
+                .time(test.Time) ...
+                .import(data);
+            exp = [ ...
+                'weather temperature=24.3,wind_direction="north" 1529933525520' newline ...
+                'weather temperature=-3.5,wind_direction="west" 1529933581618'];
+            test.verifyEqual(s.toLine(), exp);
+        end
+        
+        function imports_time_and_fields_from_timetable(test)
+            props = {test.Temperature, test.WindDirection};
+            names = {'temperature', 'wind_direction'};
+            data = timetable(test.Time, props{:}, 'VariableNames', names);
+            s = Series('weather') ...
+                .import(data);
+            exp = [ ...
+                'weather temperature=24.3,wind_direction="north" 1529933525520' newline ...
+                'weather temperature=-3.5,wind_direction="west" 1529933581618'];
+            test.verifyEqual(s.toLine(), exp);
+        end
     end
 
 end