Sort Numbers spreadsheet by how many times a value appears in a column
To isolate the rows that only have one instance of a value in the G column, use this method to simulate a pivot table. The columns of the table must have one row of headings.


Add a new column to the table.
Enter IF(COUNTIF(G$1:G1,G2)=0,COUNTIF(G,G2),"")
in the second row of the new column and autocopy down to fill the column.
Select the new column and filter for values equal to 1.


Here's an example. The new column is Count.



Select the Count column and filter for values equal to 1.