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This video demonstrates how to calculate the area mapped for each type
in a LANDFIRE grid in ArcMap. In this example
I will be calculating a percentand the acres mapped for each BpS type
in the LANDFIRE BpS grid.
I'll be working in ArcGIS 10, but a similar process can be used in
other versions of Arc. The first step is to open the attribute table
of the grid by right clicking on it in the table of contents
and selecting open attribute table. From the table
options drop down menu select export.
Name the PDF file that you will be exporting.
I like to name the file the same name as my grid
so that it is easy to identify where it came from later.
Once it is named click OK.
When asked if you would like to add the new table to ArcMap
choose No. We will open in Excel
instead. So now open up Excel
and navigate to where you saved the file. Go to File ->
Open. You will need to select
the all files option here on the right so that your dbf will become visible.
Select your file
and click open. Now to calculate the area
I'm going to insert two new columns:
one for the percent calculation and one for the acres calculation.
I like to put the new fields next to the count field
because that is used in the calculation. Now to calculate percent,
the first step is to sum the count.
I'll do that using the auto sum button. Then back up at the top
enter the formula: the percent
equals the individual cell count divided by
the total cell count
times 100 and then hit enter.
Now in order to copy and paste this formula down
the row, I need the denominator to be constant.
I can do that by inserting dollar signs
around the column letter
in the formula. Once that's done copy
and paste the formula down the column.
Now,because most of these BpS represent a fairly small
area I'm going increase the decimal place by two points
so that I can see percents less than 1.
Now, to calculate the acres
you enter the formula which is individual cell count
times point
22239
and then hit enter and you can copy and paste
that formula down the column.
Now you know an easy way to calculate the percent and the acres for a type map
in a LANDFIRE grid. Before finishing
I like to save my work in an Excel file so that I can come back to it and make
graphs and charts later.