How to count the duplicate id's within a group of a table?
3 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
Can a counter be added to a table for individual groups? For example:
- equipment_id, date, group_id, count
- 736694, 5/1/2017, 1, 1
- 736694, 5/1/2016, 1, 2
- 736694, 5/1/2015, 1, 3
- 736694, 5/1/2014, 1, 4
- 736789, 5/1/2016, 2, 1
- 736789, 5/1/2015, 2, 2
- 736789, 5/1/2015, 2, 3
- 736910, 5/1/2017, 3, 1
- 736910, 5/1/2017, 3 , 2
I am trying to view the last date entry for each equipment id.
2 comentarios
MHZ
el 27 de Nov. de 2017
Why do you need a counter? Search for the ID, then ask for the biggest date.
Respuestas (1)
Peter Perkins
el 29 de Nov. de 2017
If the table is already sorted by date and ID (use sortrows), then it's straight-forward:
>> t
t =
9×3 table
equipment_id date group_id
____________ __________ ________
736694 05/01/2017 1
736694 05/01/2016 1
736694 05/01/2015 1
736694 05/01/2014 1
736789 05/01/2016 2
736789 05/01/2015 2
736789 05/01/2015 2
736910 05/01/2017 3
736910 05/01/2017 3
>> groupCounts = accumarray(t.group_id,1)
groupCounts =
4
3
2
>> t.counter = repelem((1:3)',groupCounts)
t =
9×4 table
equipment_id date group_id counter
____________ __________ ________ _______
736694 05/01/2017 1 1
736694 05/01/2016 1 1
736694 05/01/2015 1 1
736694 05/01/2014 1 1
736789 05/01/2016 2 2
736789 05/01/2015 2 2
736789 05/01/2015 2 2
736910 05/01/2017 3 3
736910 05/01/2017 3 3
If you don't want to sort the table for some reason, then use rowfun: use group_id as a GroupingVariable, use date as an InputVariable, and make a function that returns a permutation of 1:n, "unsorted" by a column of dates.
0 comentarios
Ver también
Categorías
Más información sobre Dates and Time en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!