You can modify the display of a layer based on values of its attributes. Operations can be performed based on distinct or continuous values.

Classification by attributes based on distinct values

  1. Select and double click a layer to open a Layer properties.
  2. Click Wizard button.
  3. Select the Distinct radio button.
  4. Select the field whose values will define the layer display.
  5. Click Calculate button.
  6. Click Save button.

Colors will be automatically defined for the features but you can manually assign colors to each feature by selecting the appearance box.

 

Supported operators

It is possible to use multiple operators to combine more expressions into one. Here is the list of supported operators:

  • OR – any of the expressions have to be satisfied
  • AND – all expressions have to be satisfied
  • XOR – exclusive or – one of the expressions has to be true and the other one has to be false
  • NOT – none of the expressions have to be satisfied
  • > – greater than
  • < - less than
  • != – indicates inequality
  • >= – greater or equal
  • <= - less or equal than
  • = – equals
  • IS – equals
  • <> – exclude value
  • LOG – returns logarithmic value of the expression value
  • LN – returns natural logarithmic value of the expression value
  • SIN – returns sinus value of the expression value
  • COS – returns cosine value of the expression value
  • TAN – returns tangent value of the expression value
  • POW – returns power value of the expression value
  • SQRT – returns square root of the expression value
  • ISNULL – display features which don’t have any value

 

lyrpropdistinct

 

Classification by attributes based on continuous values

  1. Select and double click a layer to open a Layer properties.
  2. Click Wizard button.
  3. Select the Continuous radio button.
  4. Select a field whose values will define the layer display. Note that field has to be number type (Integer or Real).
  5. Choose the number of ranges that are to be defined, minimum and maximum field value.
  6. Choose Calculate.
  7. Click Save.

Colors will be automatically defined for the features but you can manually assign colors to each feature by selecting the appearance box.

lyrpropcontval

 

Manage Classes

 

  1. You can manually set an expression or add a label which will be displayed in the Layer List.
    • Expression is automatically generated field that contain information for each class. You can edit class values but make sure that there are features that satisfy condition.
    • Label is class name visible in the Layer List. Label editing will not affect data in a layer, only class name.
  2. Set category visibility.
  3. Hold the mouse button to drag the expression to a different position.
  4. Select Appearance to change the defined color.
  5. Remove or add expressions.

lyrprop2

See also:

Tutorial 2: Classification and appearance settings