Example TGGHor.0: Suppose $y$ is a function of $x$ given by the equation $y = f (x) = 2x+ 3$.
The table, graph, and mapping diagram of this function have been created using GeoGebra.

In this mapping diagram, the axes are horizontal and the arrows point vertically from source axis down to target axis.
You can change the function by entering the value for $f(x)$ in the box of either the mapping diagram or the graph.

This visualization is not preferred:

• To match the table, the table would have to be laid out horizontally.
• It will match the $X$ axis on the graph, but not the $Y$ axis on the graph.
  
• This does not match with an interpretaion of the function value as an object's height above,ground level.
• It is often used because of it space saving for typesetting on a printed page.
• It has some advanced benefit when thinking of mappings as projections, as from the sun onto the earth.
  

GeoGebra: Table, graph, and mapping diagram (Horizontal Axes).