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Thread: ArcMap 10: calculating area of selected polygons/features

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    Cyburbia Administrator Dan's avatar
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    ArcMap 10: calculating area of selected polygons/features

    The title line is the question. If I select a number of polygons or features, how can I calculate the cumulative area (acres, whatever) of them?

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    Cyburbian
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    Open the layer's attribute table. If there isn't one already, add a field. Use the double field type as you will be including a decimal. Run the Field Calculator to compute the acreage.
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    Cyburbia Administrator Dan's avatar
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    Quote Originally posted by nrschmid View post
    Open the layer's attribute table. If there isn't one already, add a field. Use the double field type as you will be including a decimal. Run the Field Calculator to compute the acreage.
    Thanks! I did that previously, though, and it calculated the area for each individual polygon. How about for selected ploygons?

    EDIT: Got it, I think.. View table with selected polygons, right click on area, statistics.
    Growth for growth's sake is the ideology of the cancer cell. -- Edward Abbey

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    Cyburbian
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    Personally I just get the values of the selected polygons into Excel and AutoSum them. I'm honestly not sure how else you can do that in Arc without merging polygons.

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    Cyburbian
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    Thanks! I did that previously, though, and it calculated the area for each individual polygon. How about for selected ploygons?
    I'm still at 9.3, but there should be something similar in 10. Right click on the area field you created, and click "Statistics". The little popup window should have what you're looking for. Alternately, click "Summarize" to output similar info as a table or text file.

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    Cyburbian
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    Quote Originally posted by Blide View post
    Personally I just get the values of the selected polygons into Excel and AutoSum them. I'm honestly not sure how else you can do that in Arc without merging polygons.
    I would do the same in Excel. You don't have to merge polygons (or export select features as a new shapefile). I am pretty sure there would is some SQL expression that can total all of the values (or values of selected features) and add that value into a new cell in a new column.
    "This is great, honey. What's the crunchy stuff?"
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    open up the attribute table ---> at the bottom you have 2 icons (show all records or show selected) click on show selected -- > rt click on the area field (or add new field) Calculate Geometry --> select your measurement type (acres, sq/ft etc...)

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    Cyburbian DetroitPlanner's avatar
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    I had to use the field calculator last week. It is much improved over 9.
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    Easiest way

    Y'all are making it WAAAY to complecated. All you need to do is select the polygons you want to sum, then open the attribute table and right click on the column with the area in it and select summarize. That will give you the sum of the area of the selected polygons.

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    Related Question: Selectingpart of a polygon based on a pre determined area size

    Hello i was wondering if anyone can suggest a way to select an area within an existing polygon based on a particular area size?

    E.g. Say for example i have a large soils polygon of 100 hectares and i wanted to select only 50 hectares within that polygon and use that to create a layer, how would i acheive this?

    Cheers any help would be appreciated

  11. #11
    Cyburbian
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    Quote Originally posted by joshfisher View post
    Hello i was wondering if anyone can suggest a way to select an area within an existing polygon based on a particular area size?

    E.g. Say for example i have a large soils polygon of 100 hectares and i wanted to select only 50 hectares within that polygon and use that to create a layer, how would i acheive this?

    Cheers any help would be appreciated
    You can use the Select by Attributes wizard to define which area size to select, i.e. "Select from SOIL where AREA <50". Or, you can select the features you want manually, either in an attribute table or by clicking on the polygon itself.

    Once you have your selection, right-click your layer in the table of contents, select Data -> Export Data, and then make sure you have "Export Selected Features".

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