How to read HDFS file as input matrix - getting error "Error in FUN(X[[2L]], ...) : Sorry, parameter type `NA' is ambiguous or not supported."

Question

When I am reading a HDFS file as input matrix for mapreduce function (within rmr2 package) in my R script, I am getting the below error.

> r.file <- hdfs.file("hdfs://X.X.X.X:NNNN/somnath/merged_train/part-m-00000","r")
> input = as.matrix(hdfs.read.text.file(r.file)) 
Error in FUN(X[[2L]], ...) :   Sorry, parameter type `NA' is ambiguous or not supported.

Can anybody suggest how to read a file stored in HDFS as an input matrix? Any insightful help will be greatly appreciated and accordingly rewarded.

Thanks in advance, Somnath