When symbolizing a numeric field in ArcMap in the Layer Properties dialog box on the Symbology tab under Quantities and under Graduated colors, a blank Field Value drop-down list results from generating data using the CSV file.
String fields cannot be symbolized. Symbolizing by quantity requires a numeric field.
In the Symbology tab, the Graduated colors option is often used to symbolize the fill of a polygon with quantities. Quantities are typically used with quantitative data or numeric fields, while categories are typically used with qualitative data, string fields, or text fields.
Solution or Workaround
A schema.ini file must be created to override the field data type from the delimited text file (CSV file).
- Add the CSV file into ArcMap.
- In the Table of Contents, right-click the CSV file, and select Data > Export...
- Save the CSV file. For 'Save as type:', select Text File, and change the extension to .csv instead of .txt. Click Save > OK.
- Using Windows Explorer, browse to where the CSV file is saved. A schema.ini file is created.
- Using Notepad, right-click the schema.ini file, and select Edit.
- Change the text values to Double.
Once completed, users may select the Double field in the drop-down list when symbolizing in the Symbology tab.