{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-05-26T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":49768,"title":"Find the worst traffic yesterday","description":"A traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.","description_html":"\u003cdiv style = \"text-align: start; line-height: 20.44px; min-height: 0px; white-space: normal; color: rgb(0, 0, 0); font-family: Menlo, Monaco, Consolas, monospace; font-style: normal; font-size: 14px; font-weight: 400; text-decoration: none solid rgb(0, 0, 0); white-space: normal; \"\u003e\u003cdiv style=\"block-size: 83.9583px; display: block; min-width: 0px; padding-block-start: 0px; padding-top: 0px; perspective-origin: 406.493px 41.9792px; transform-origin: 406.493px 41.9792px; vertical-align: baseline; \"\u003e\u003cdiv style=\"font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 383.49px 41.9792px; text-align: left; transform-origin: 383.498px 41.9792px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; \"\u003e\u003cspan style=\"block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 0px 0px; transform-origin: 0px 0px; \"\u003e\u003cspan style=\"\"\u003eA traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.\u003c/span\u003e\u003c/span\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e","function_template":"function y = bestTime(x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = 38629;\r\nmyCars=thingSpeakRead(38629,'numdays',1,'outputformat','timetable');\r\n[value,carIndex]=max([myCars.DensityOfEastboundCars myCars.DensityOfWestboundCars]);\r\n[val,theSpot]=max(value);\r\ny_correct =  myCars.Timestamps(carIndex(theSpot));\r\nassert(isequal(bestTime(x),y_correct))","published":true,"deleted":false,"likes_count":1,"comments_count":1,"created_by":161547,"edited_by":161547,"edited_at":"2022-10-24T15:08:26.000Z","deleted_by":null,"deleted_at":null,"solvers_count":28,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2021-01-05T14:15:08.000Z","updated_at":"2026-04-20T11:33:57.000Z","published_at":"2021-01-05T20:57:01.000Z","restored_at":null,"restored_by":null,"spam":null,"simulink":false,"admin_reviewed":false,"description_opc":"{\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eA traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\",\"relationship\":null}],\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"target\":\"/matlab/document.xml\",\"relationshipId\":\"rId1\"}]}"}],"problem_search":{"problems":[{"id":49768,"title":"Find the worst traffic yesterday","description":"A traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.","description_html":"\u003cdiv style = \"text-align: start; line-height: 20.44px; min-height: 0px; white-space: normal; color: rgb(0, 0, 0); font-family: Menlo, Monaco, Consolas, monospace; font-style: normal; font-size: 14px; font-weight: 400; text-decoration: none solid rgb(0, 0, 0); white-space: normal; \"\u003e\u003cdiv style=\"block-size: 83.9583px; display: block; min-width: 0px; padding-block-start: 0px; padding-top: 0px; perspective-origin: 406.493px 41.9792px; transform-origin: 406.493px 41.9792px; vertical-align: baseline; \"\u003e\u003cdiv style=\"font-family: Helvetica, Arial, sans-serif; line-height: 21px; margin-block-end: 9px; margin-block-start: 2px; margin-bottom: 9px; margin-inline-end: 10px; margin-inline-start: 4px; margin-left: 4px; margin-right: 10px; margin-top: 2px; perspective-origin: 383.49px 41.9792px; text-align: left; transform-origin: 383.498px 41.9792px; white-space: pre-wrap; margin-left: 4px; margin-top: 2px; margin-bottom: 9px; margin-right: 10px; \"\u003e\u003cspan style=\"block-size: auto; display: inline; margin-block-end: 0px; margin-block-start: 0px; margin-bottom: 0px; margin-inline-end: 0px; margin-inline-start: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; perspective-origin: 0px 0px; transform-origin: 0px 0px; \"\u003e\u003cspan style=\"\"\u003eA traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.\u003c/span\u003e\u003c/span\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e","function_template":"function y = bestTime(x)\r\n  y = x;\r\nend","test_suite":"%%\r\nx = 38629;\r\nmyCars=thingSpeakRead(38629,'numdays',1,'outputformat','timetable');\r\n[value,carIndex]=max([myCars.DensityOfEastboundCars myCars.DensityOfWestboundCars]);\r\n[val,theSpot]=max(value);\r\ny_correct =  myCars.Timestamps(carIndex(theSpot));\r\nassert(isequal(bestTime(x),y_correct))","published":true,"deleted":false,"likes_count":1,"comments_count":1,"created_by":161547,"edited_by":161547,"edited_at":"2022-10-24T15:08:26.000Z","deleted_by":null,"deleted_at":null,"solvers_count":28,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":1,"created_at":"2021-01-05T14:15:08.000Z","updated_at":"2026-04-20T11:33:57.000Z","published_at":"2021-01-05T20:57:01.000Z","restored_at":null,"restored_by":null,"spam":null,"simulink":false,"admin_reviewed":false,"description_opc":"{\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003cw:jc w:val=\\\"left\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eA traffic monitoring system records traffic density for the highway in front of the MathWorks headquarters using a raspberry pi with a webcam.  There is Simulink code deployed to the device which writes the sum of the observed traffic density every 15 seconds to ThingSpeak channel 38629. Create a function that uses the channel ID and returns the timestamp when the traffic was highest in the last 24 hours. If there are duplicate values, return the first.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\",\"relationship\":null}],\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"target\":\"/matlab/document.xml\",\"relationshipId\":\"rId1\"}]}"}],"errors":[],"facets":[[],[{"value":"easy","count":1,"selected":false}]],"term":"tag:\"thingspeak\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}