Typically, you would compare values using a token, such as "@Data.value~ < 0" or "@Session.ShowCol1~=='true'". Elements are removed when the Condition evaluates to False.
Use quotes when working with strings:
"@Data.myColumn~" == "SomeValue"
If your data token may have a double quote inside of it, you should use single quotes:
'@Data.myColumn~' == 'SomeValue'
String valued data tokens with single and double quotes inside are not supported by the condition attribute.