GEOG 3LT3 Lecture Notes - Lecture 12: Incidence Matrix, Address Plus Port
2 May 2018
School
Department
Course
Professor
October 31, 2016
Measures of connectivity (dominance)
- For this network we will assume the length of each link is the same or that the
travel time is identical
- We can define the connectivity matrix for this plot
- We can translate this figure into a matrix by converting it to an incidence matrix
- Our matrix will have 7 rows and 7 columns
o0’s are assigned to the nodes at themselves 0x0 because a node is not
connected to itself
oA 1 is assigned to an incident when 2 nodes connect (are linked)
▪He is also assuming that the links here a bidirectional
oP here is a vector
▪We have 7 nodes and we have 1 cell for each node to store the
information about each node
•In this case the information we are interested in is the
number of opportunities
▪If P had been a row then it would be P’ and be the transpose of P
•Here Aij turns to Aji
▪Transpose is used sometimes when we need to use the data in a
different way (he didn’t explain why we might need to do this)
▪When would we be interested in cxp? A = C x P
•Here we would multiply the first row by the first column (then
he added up each individual multiplication product)
•The first sum is 3 and second would be 5, 3rd would be 5
•We can do this type of math for every CxP product
•A+P will be accessibility plus (potential, I think he said) it was
hard to understand
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