Plot network graph by rolling period using R - r

Question

I was trying to conduct the network graph and some statistics by rolling three-year period, but I don't know how to set the rolling function. Below is my coding without rolling.
> library(igraph)
> em <- read.csv(file.choose(), header = TRUE )
> network <- graph.data.frame(em, directed = TRUE )
> em
sender receiver weights year
1 a d 2 2001
2 b a 3 2001
3 c a 1 2001
4 d h 1 2001
5 e d 3 2001
6 a b 1 2002
7 b c 2 2002
8 c d 1 2002
9 d a 1 2002
10 e h 2 2002
11 a d 1 2003
12 b d 1 2003
13 c a 2 2003
14 d h 2 2003
15 e a 1 2003
16 a d 1 2004
17 b c 1 2004
18 c d 2 2004
19 d c 1 2004
20 e a 2 2004
> E(network)$weight <- as.numeric(network[,3])
Warning message:
In eattrs[[name]][index] <- value :
number of items to replace is not a multiple of replacement length
> p <- plot (network,edge.width=E(network)$weight)
So in this example eventually it would come up with one weighed network graph. I would like to conduct the graphs using data in 2001-2003 and 2002-2004 subsamples, further with some SNA statistics. Some online resource suggests -rollappy()- or the functions in package -tidyquant- could do, but I didn't manage to figure our how to recognise the 4th column as year and how to set the rolling period. Would much appreciate it if anyone can help out, as I am a newbie to R.
Many thanks!!

Answer 1

Thanks #emilliman5 for the further questions.
My real dataset is an unbalanced panel with 15-year time span. I was intended to conduct network graphs using part of the full data. Subtracting rule is the 3-year rolling period (in fact with some other conditions but I just asked rolling here). So I planned to call the rolling subsamples first and conduct graphs. I hope it is a bit clear now.
Above data was just a mock sample. 4-year range should generate two graphs (2001-2003, 2002-2004), and 15-year should come up with 13 graphs. The real weighting variable is not called weight, but I agree the line "as.numeric(network[,3])" is redundant. (I realise now the example I made wasn't good...sorry...)
I get someone helped me with that now, so I'll just post some of the codes. Hope it might help other people.
Method 1: call sub-samples by function. This save me from constructing the nested loops together with graphing.
# Function: conditions for substracting; here rolling-year only
f <- function(j){
df <- subset(em, year>=j & year <= j+2)
}
print (f(2001)) # Test function output, print-out
# Rolling by location and year, graph-plotting
for (j in 2001:2002){
sdf = f(j)
nw <- graph.data.frame(sdf, directed = TRUE)
plot(nw, edge.width = E(sdf[[j]])$weight)
}
Method 2: Use loops -- fine for one or two subtracting conditions but would be a bit clumsy for more.
c <- 2001 # a number for year count
sdf <- {} # Set an empty set to save subsets
for (j in 2001:2002){
df_temp <- subset(em, year>=j & year<=j+2)
print(nrow(df_temp)) # To check the subset, not necessary
sdf[[c]] <- cbind(df_temp)
nw <- graph.data.frame(sdf[[c]], directed = TRUE)
plot(nw, edge.width = E(sdf[[c]])$weight)
c <- c + 1
}