library(ncdf4)
OSND_gpmr.df<-NULL

GPM_R.files= list.files(path,pattern='*.nc4',full.names=TRUE)

for(i in seq_along(GPM_R.files)) {
  nc_data = nc_open(GPM_R.files[i])

  GPM_Prec<-ncvar_get(nc_data, 'IRprecipitation')

  x=dim(GPM_Prec)

  ### note start=c(42,28) are the index in image regards to real coordinates of interset
  ## R reads images from lat,long.
  OSND_gpmr.spec =ncvar_get(nc_data, 'IRprecipitation', start = c(42,28), count = c(1,1))
  rbind(OSND_gpmr.df,data.frame(OSND_gpmr.spec))->OSND_gpmr.df

  nc_close(nc_data)
}