[igraph] Creating subgraphs on the basis of clusters()

[MATSUDA, Noriyuki]

Hello:

 I need help in creating subgraphs by selecting clusters of certain sizes.  To
do so, I want to obtain the list of memberships of the vertices to be selected.
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a <- c(0,1)
b <- c(2,3,3,4)
c <- c(5,6,5,7,6,7)
d <- c(8,9,8,10,8,11, 9,10,9,11, 10,11)
e <- c(12,13,12,15, 13,14, 14,15, 15,16)
g<- graph(c(a,b,c,d,e),directed=F)
plot(g, layout= layout.circle) #vertex.label=V(g)$name
cls<- clusters(g)
# $membership
#  [1] 0 0 1 1 1 2 2 2 3 3 3 3 4 4 4 4 4
# $csize
# [1] 2 3 3 4 5   #e.g., the membership & the size of the first 
cluster are 0 & 2

clsID<- which(cls$size == 2) - 1     # resulting in a single value 0
which(cls$membership == clsID)  # 1, 2
clsID<- which(cls$csize == 3) - 1  # resulting in a vector consisted of 1 & 2
which(cls$membership == clsID)  # resulting in 0 0 which are hard to interpret.
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  Is there a way to specify the condition like cls$membership in clsID ?
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MATSUDA, Noriyuki　<in Kanji> 松 田 紀 之