If you want distance from the first point in a data table to every other point in sequence, then use cumulative distance function below.
Do the following:
- select Python parser
- toogle on Show code block
- paste the following in the Pre-logic Script Code block
- and the last piece in the expression box
Pre-logic Script Code:
""" input shape field: returns cumulative distance between points
dist_cumu(!Shape!) #enter into the expression box"""
x0 = 0.0; y0 = 0.0; distance = 0.0
def dist_cumu(shape):
global x0; global y0; global distance
x = shape.firstpoint.X; y = shape.firstpoint.Y
if x0 == 0.0 and y0 == 0.0:
x0 = x; y0 = y
distance += math.sqrt((x - x0)**2 + (y - y0)**2)
x0 = x; y0 = y
return distance
should do it... syntax highlighting isn't taking this morning