I would like to join the attributes of one polygon layer to another polygon layer by their common ID. The problem is that in layer A, each ID has multiple rows, because each represent shapes from the layer B cut in multiple pieces (intersected with other information) and I need that information to be replicated each time within the boundaries of the layer B. Is there a way to join by attribute, so that the target layer B repeats rows of the adjoining Layer A, when the ID in Layer A occurs multiple times?
[GIS] Join by attribute when unique identifier has multiple rows using ArcMap 10.2
arcgis-desktopattribute-joinsattribute-tablefields-attributesgeoprocessing
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I see two options:
- Ensure that your line dataset has a unique id field. Intersect the lines and polygons. Calculate the lengths of the output lines. Select the record with the max length for each line id. Delete all other lines (switch selection and delete). Table join the max length lines to original lines using the unique id. Field calculator to populate the census block field from joined table. Remove join.
- Spatial join the polygons to the lines and use the match option as 'Have their center in'.
Method 1 will be more accurate, method 2 will be faster.
This can be done by something that is called Merge rule - not very easy to find, I think.
Use the Spatial Join geoprocessing tool and choose the Merge rule to be Sum for the needed fields (right-click each field). In the image below, I am joining the cities to the states (and each city feature has an integer associated with each of those fields you mentioned).
Then the output fields will have a sum for all values in each field.
You can check the results by right-clicking a field in the point feature class and choosing Statistics to see the sum, pretty handy.
As a comment, you may consider redesigning your table with incidents. I would suggest keeping two fields: Date and Type. This is much better because if you would need to log a new type of incident, you wouldn't need to add a new field. Of course, you could also run Spatial Join just getting the total number of points within each polygon and since each point can only have single type, it would be a matter of running simple summary statistics on the output.
Best Answer
I would suggest you start by reviewing the help files on Joins so that you understand the relationship types (one-to-one, one-to-many, many-to-one, many-to-many) and their implications.
Yes, there are two ways to do what you want. However I do want to point out (if it's not already clear and desired) you're going to end up with A number of B polygons stacked on top of each other unless you're trying to combine those attributes, which would be aggregation. I'm not entirely clear on what result you're trying to achieve. It doesn't make a lot of sense to apply a single attribute value from a piece to a whole.
A regular join does not support one-to-many relationships. It will only return the first found record. However a Spatial Join does have an option to support one-to-many and should work in this case since your A's are derived from your B's. The other option is the Make Query Table tool, the results of which have to be saved to be made permanent.