Make Boolean Expressions

Make Boolean Expressions

Boolean expressions are expressions that can either be true or false. They are useful in creating filters. For example, if you're looking at population data and you want to find women over 60 who are either married or divorced, then the expression below will filter out from the plot any people in the census file that do not fit this category.

Here are some tips for making Boolean expressions.

•The comparison operators =, <, and > can be found on the formula editor's keypad. You can also find ≤, ≥, and ≠ on the keypad by pressing Ctrl (Win) Option (Mac). You can also enter all of these from the computer keyboard.

•Express the not of an expression (the negative of an expression) by positioning the cursor in front of the expression and clicking the not key on the formula editor keypad.

•You can use and and or to string logical expressions together. Click the buttons on the formula editor keypad to enter these. Typing the words from the computer keyboard does not work.

•Some keyboard shortcuts: & for and, Ctrl+Shift+O for or, and ~ for not.

•When in doubt about which expressions are evaluated first, use parentheses to force the evaluation order you want.

•True and false are allowed values for attributes, so you can enter a formula for an attribute that returns a Boolean value.