In a Power Automate array Group By on 1 column and concatenate text in

Question

I have below Array in Power Automate: { 'body': { 'name': 'vAnswersArray', 'type': 'Array', 'value': [ { 'Index': 0, 'Title': 'AC-01', 'Answer': 'test ac01 a' }, { 'Index': 1, 'Title': 'AC-02', 'Answer': 'test ac02 a' }, { 'Index': 2, 'Title': 'AC-03', 'Answer': 'test ac03 a' }, { 'Index': 3, 'Title': 'AC-04', 'Answer': 'test ac04 a' }, { 'Index': 4, 'Title': 'AC-01', 'Answer': 'test ac01 b' }, { 'Index': 5, 'Title': 'AC-03', 'Answer': 'test ac03 b' } ] } } My question is, I want to Group by on Title column and concatenate text in Answer column, so how to get below output: 'value': [ { 'Index': 0, 'Title': 'AC-01', 'Answer': 'test ac01 a 
 test ac01 b' }, { 'Index': 1, 'Title': 'AC-02', 'Answer': 'test ac02 a' }, { 'Index': 2, 'Title': 'AC-03', 'Answer': 'test ac03 a 
 test ac03 b' }, { 'Index': 3, 'Title': 'AC-04', 'Answer': 'test ac04 a' } ] Index column need not come in output. I appreciate all answers, Thanks.

Raghunath Bhukan · Answer

Hi, you can do it multiple ways. Solution 1 - Step 1: Initialize variables Initialize an Array variable Name: GroupedArray Value: [] Initialize a String variable Name: AnswerText Value: empty Step 2: Get distinct Titles Add a Compose action called DistinctTitles and use this expression: union( select(variables('vAnswersArray'), item()?['Title']), select(variables('vAnswersArray'), item()?['Title']) ) This gives you a unique list of Titles. Step 3: Apply to each Title Add Apply to each Input: outputs('DistinctTitles') Inside the loop: Step 4: Filter array by Title Add Filter array From: variables('vAnswersArray') Condition: item()?['Title'] is equal to items('Apply_to_each') Step 5: Build concatenated Answer text Add Compose action called CombinedAnswers with this expression: join( select(body('Filter_array'), item()?['Answer']), '
' ) This joins all matching answers with a new line. Step 6: Append grouped result Add Append to array variable Variable: GroupedArray Value: { "Title": "@{items('Apply_to_each')}", "Answer": "@{outputs('CombinedAnswers')}" } Final Output ( GroupedArray ) [ { "Title": "AC-01", "Answer": "test ac01 a 
 test ac01 b" }, { "Title": "AC-02", "Answer": "test ac02 a" }, { "Title": "AC-03", "Answer": "test ac03 a 
 test ac03 b" }, { "Title": "AC-04", "Answer": "test ac04 a" } ] Final output with Grouped by Title, Answers concatenated, Index removed, Order preserved based on first occurrence Solution 2- Below is the fastest-performance solution in Power Automate . It is optimized for large arrays , uses one pass over the data , and avoids nested filter() calls (which are slow). Fastest approach (single-pass dictionary build + projection) Use ONE Compose action with the expression below. select( keys(outputs('BuildDictionary')), { 'Title': item(), 'Answer': outputs('BuildDictionary')?[item()] } ) Then add ONE more Compose before it named BuildDictionary : reduce( variables('vAnswersArray'), createObject(), lambda( 'acc', 'cur', setProperty( acc, cur()?['Title'], if( equals(acc?[cur()?['Title']], null), cur()?['Answer'], concat(acc?[cur()?['Title']], '
', cur()?['Answer']) ) ) ) ) That’s it — two Composes total , no loops, no filters. Final output [ { "Title": "AC-01", "Answer": "test ac01 a 
 test ac01 b" }, { "Title": "AC-02", "Answer": "test ac02 a" }, { "Title": "AC-03", "Answer": "test ac03 a 
 test ac03 b" }, { "Title": "AC-04", "Answer": "test ac04 a" } ] Why this is the fastest possible solution reduce() loops once over the array (O(n)) Data is stored in a dictionary (hash lookup, O(1)) No nested filter() or select() inside loops No variables or Apply to each Memory efficient and scalable Thanks.

In a Power Automate array Group By on 1 column and concatenate text in

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