I have 4 parallel arrays based on a table representing attributes of a map. Each array has approx. 500 values, but all have the same number of values.

The arrays are:

`start` = location of the endpoint with the smaller flow accumulation,

`end` = location of the other endpoint (with the larger flow accumulation),

`length` = segment length, and; 

`shape` = actual shape, oriented to run from start to end.

I am attempting to create a data structure from which I can use a recursive function on to determine the start and end points every 2000m along the length.

The following question and answer describe what I am attempting to accomplish:

<https://gis.stackexchange.com/questions/87649/select-points-approx-2000-metres-from-another-point-along-a-river>

How do I store these 4 parallel arrays in a dictionary keyed by start?

I am new to writing functions, dictionaries and using arrays in dictionaries. I am attempting to do this task in Python.