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I have a polygon shapefile that contains multiple lakes. Some of these lakes have multiple residuals. I have all of the residuals for the lakes in an Excel file, and I want to show residuals for the lakes as dots proportional to the size of the residual to see if the size of the residual is influenced by geographic location.

I did a relate, but how would I show all the residuals as symbols on top of the map of lakes?

This is when there is only one residual per lake. However, I had multiple samples from the lake.

This is an image of when there is only one residual per lake. However, I had multiple samples from the lake.

CodingGrandma
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2 Answers2

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Try using the feature to point geoprocessing tool to convert the lakes to points. From there you can set a proportional symbology on the new point layer and define based on your residual data.

amasephy
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Multiple techniques are possible, e.g. you can calculate number of records in related table and generate random points inside lakes. There is a risk of points sitting to close. Another nice solution to place relevant number of points on inside buffer outline. Time consuming and requires split of lines into equal parts.

I used this formulae to compute XY of residuals in related table:

[INSIDE_X]+ [theDist] *Cos ( ([Group_No]-1)*6.28318530717959/[Count] )/2
[INSIDE_Y] + [theDist] *Sin ( ([Group_No]-1)*6.28318530717959/[Count] )/2

and to place points around lake centre making sure they are well dispersed:

enter image description here

Related table:

enter image description here

To compute lake centroids and distance to lake outline (INSIDE_X,INSIDE_Y,theDist) I used script from here, applied it on lakes and transferred results to related table using join by attributes. To compute Group_No I used field calculator expression from here. Count is total count of residuals inside lake, use summarise statistics to compute it.

FelixIP
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