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Attributes in ArcGIS. ArcGIS Attributes. FID – ESRI’s internal identifier Shape – Actual spatial data. Adding Fields. Make sure the Shapefile is not marked as Read-Only Make sure you’re not in an edit session Select “Add Field” from the Options menu Name the field Select the type of data - PowerPoint PPT Presentation
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ArcGIS Attributes• FID – ESRI’s internal identifier• Shape – Actual spatial data
Adding Fields• Make sure the Shapefile is not marked
as Read-Only• Make sure you’re not in an edit session• Select “Add Field” from the Options
menu• Name the field• Select the type of data• Careful with “Precision”
Checking the Shapefile• Use the “File Explorer” or “My Computer”• Select all the files for the Shapefile by:
– Shift-clicking each file– Drag the cursor over all of them
• Right click on one of the selected files• If “Read-only” is checked:
– Uncheck it– Click “OK”
Checking the edit session• Right click on the menu bar• Select “Editor”• If “Start Editing” is grayed out:
– Select “Stop Editing”
Naming Fields
• Arc only allows 10 characters• Remember you’ll be using the Name in
calculations and queries!
Select the Field Properties• If you change the precision or scale:
– Arc map may change the type for you!• Types:
– Short Integer: 16-bit integer (5 digits)– Long Integer: 32-bit integer (9 digits)– Float: 32-bit floating point – Double: 64-bit floating point – Text: up to 254 characters– Date: MM/DD/YYYY format
Precision can change “Type”• ArcGIS will change the “Type” if you put
in a precision that is beyond the specified type
Editing Attribute Values• The attribute “table” contains rows and
columns similar to a spreadsheet• However, it’s history and future are
based on databases:– Columns=Fields– Rows=Records
• We can add and delete columns (fields)• Adding and deleting features adds and
deletes rows
Editing Attribute Values
• If attributes won’t change:– Make sure you’re in an edit session
• Double click on the cell to type in a new value
• Use the “Field Calculator” to change entire columns
Starting an Edit Session• Without an Edit Session – ArcGIS will
not track your changes so “Undo” will not work!
Making Changes• Click (or double-click) in the cell• Type changes – easy!
– Dates are in MM/DD/YYYY format
Stop Editing!• If you don’t select “Stop Editing”, your
changes will not be saved
Coordinate Attributes• It is common to see Lat/Lon or
Easting/Northing in attribute tables for point layers
• These are not the values used to render the spatial data!
• These values are not updated when you project, edit, or transform the spatial data!
• To update these columns…
Selection• Selection tab on TOC• Manual Selection
– Click to select– Shift-click to add/remove from selection
• Select by Attributes• Select by Location• Right click on layer -> Selection ->
Create Layer From Selected Features– Then, “Export” the data to a new file
Select by Attributes• SELECT * FROM TableName WHERE:
– “WHERE Clause” or Filters
