How to Position Aesthetics

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Basic aesthetic properties that you use in Stagraph are position properties of the selected geometry in a 2D space. This position can be defined by parameters x and y. In some cases, it may be even more of these parameters. An example would be geom_boxplot. This geometry can be defined by the parameters x and y (program automatically calculates statistical variables) or by parameters x, ymin, lower, middle, upper and ymax (set direct varaibles from the dataset). More about these specific cases will be mentioned in sections for individual geometries.

If you set in Plot Panel as data property the dataset that you use, you can choose from aes combo-boxes variables that you want to map as the position aesthetics. As with other aesthetic properties, you can use selected variable from dataset or its combination (as equation in R language). The first example uses mtcars dataset and as position aesthetics are used variables mpg and cyl.

Program automatically detects the data type of variable and creates continuous (numeric values, integer, date, time, datetime) or categorical scale (string). Sometimes, it may happen that the values you use has continuous nature (e.g. integer), but you want to use them as categorical variable. As an example, we can use previous figure, where the values on Y axis are integers. Program automatically creates for them continual scale. In our example, the dataset does not contain values 5 and 7 and on the scale they take up an unnecessaey space. In this case it would be appropriate to use them as categorical values and display only those that occurred in the dataset. This transformation can be accomplished easily. Just enclose the variable in parentheses and write before the R function factor. This function transforms continual values to categorical and displays them in plot using the categorical scale.

Now, on the axis are not longer displayed values 5 and 7. Then you can, for example, change their order using the function scale_y_discrete.

Further, you can define the position as a function of several dataset variables. You can, for example, define Y axis as the ratio between variables disp and cyl. The position property is defined as follows:

disp / cyl

If you want use the logarithm of X variable, just use the following record:

log(mpg)

The result of such position is in the following figure.

Every time you choose varialble from the aes combo-box, the current value in the text-box will be overwritten by the new value. If you want to pass a value to text-box at the end of current content, hold the SHIFT key at the combo-box selection.

Another example shows how you can define your graph as 1D visualization. One axis (e.g. X) is defined by variable from the dataset. The second is defined as a single value. You can use value in numeric or string format (enclosed in quotation marks). After drawing, points are on the Y axis located on one line. Then you can use the Position Scales function to hide the title and marker of Y axis and your grah will be visually indentical to the classic 1D plot.