Here is some quick and dirty code for entering an adjacency matrix into R. These data were originally manipulated in Excel 2010 and saved as a comma delimitated *.csv file. The original file had sorted actor names down the first column and the same names along the first row. No value was present in the upper lefthand cell of the original data matrix.

# Load network data
# Expected format: adjacency matrix with corresponding row and column names
# Expected file type: *.csv
year1<-read.csv("networkData.csv",header=FALSE,stringsAsFactors=FALSE,sep=",")
rNames<-year1[-1,1]                                   # Get row names
cNames<-as.vector(as.character(year1[1,-1]))          # Get column names
year1<-apply(as.matrix(year1[-1,-1]),2,as.numeric)    # Get network matrix
year1[is.na(year1)]<-0                                # Set missing ties to 0
row.names(year1)<-rNames                              # Give row names
colnames(year1)<-cNames                               # Give column names