Two Special Data Validations

The GIS user knows on which side of the inter-marker line the tree was planted, so the correct intersection is selected and its coordinates read off in the GIS window (or the intersection is added as a point feature in a “trees” layer ):

A second method is to calculate the locations of those two circle intersections using trigonometry, then select the correct intersection by inspection of the coordinates. If the input data are correct, then the tree and the marker pegs form a triangle in which the sum of the lengths of any two sides is greater than or equal to the length of the remaining side. In a shell script where the distance variables are d1, d2 and d3, the test is:

In a recent BASHing data post I showed one way to number “irregular” multi-line records.

Source: www.datafix.com.au