Chapter 3 Graph Modification

3.1 Load plot “House”

g1 <- make_graph("house")
#data structure - full
g1[]

## 5 x 5 sparse Matrix of class "dgCMatrix"
##               
## [1,] . 1 1 . .
## [2,] 1 . . 1 .
## [3,] 1 . . 1 1
## [4,] . 1 1 . 1
## [5,] . . 1 1 .

#data structure - row 1
g1[1, ]

## [1] 0 1 1 0 0

#data structure - col 2
g1[, 2]

## [1] 1 0 0 1 0

par(mfrow = c(1, 2))
#plot graph object
plot(g1,
     vertex.size = 30,
     vertex.color = 1, #default
     main = "Our House"
     )
#assign attribute & label nodes
vertex_attr(g1, name = "rooms") <- c("LR", "FR", "BR", "DR", "Garage")
plot(g1,
     vertex.size = 30,
     vertex.color = 1,
     vertex.label = V(g1)$rooms,
     main = "Has Many Rooms"
     )

3.2 Get Edges

# "E" is for edges
E(g1)

## + 6/6 edges from ded6328:
## [1] 1--2 1--3 2--4 3--4 3--5 4--5

edge_attr(g1, name = "services") <- c("electric", "air_cond", "gas", "cable", "wifi", "water")
par(mfrow = c(1, 2))
plot(g1,
     vertex.size = 30,
     vertex.color = 1,
     vertex.label = V(g1)$rooms,
     main = "With Many Rooms"
     )
plot(g1, 
     vertex.size = 30,
     vertex.color = 1,
     vertex.label = V(g1)$rooms,
     edge.label = E(g1)$services,
     main = "Is Connected"
     )

3.3 Get Vertices

# "V" is for vertices
V(g1)

## + 5/5 vertices, from ded6328:
## [1] 1 2 3 4 5

3.3.1 Add vertices attribute

V(g1)$label <- letters[1:length(V(g1))]
#query attibutes
vertex_attr(g1)

## $rooms
## [1] "LR"     "FR"     "BR"     "DR"     "Garage"
## 
## $label
## [1] "a" "b" "c" "d" "e"

#set_vertex_attr(g1, name = "size", value = seq(10, 50, by =10))
V(g1)$size <- seq(10, 50, by = 10)
plot(g1)