Mnn <- function(X,M){
  m <- matrix(0,nrow(X),nrow(X))
  m <- as.data.frame(as.matrix(dist(X)))
  m[row(m)==col(m)] <- Inf
  m <- t(apply(m,1,order)[1:M,])
  m <- as.matrix(m)
  return(m)
}
Mnn_graph <- function(S){
 m <- as.data.frame(S)
 m <- mutate(m,Id = 1:nrow(S))
 m <- reshape2::melt(m,id="Id")
 edges <- m[,c(1,3)]
 m <- as.matrix(get.adjacency(graph.data.frame(edges))) #otrrzymujemy macierz sąsiedztwa
 gra <- graph.adjacency(m) #robimy graf z tej macierzy
 com <- components(gra) #szukamy skladowych
 comp <- igraph::groups(com)#zwracamy skladowe
 if(length(comp)==1){
   m <- as.matrix(m)
   return(m)
 }
 elem <- lapply(comp, `[[`, 1) #bierzemy po jednym elemencie z kazdej skladowej aby uspojnic graf
 elem <- unlist(elem)
 for(i in 1:length(elem)){
   m[elem[i-1],elem[i]] <- 1
   m[elem[i],elem[i-1]] <- 1
 }
 m <- as.matrix(m)
 return(m)
}
Laplacian_eigen <- function(G,k){
  m <- graph.adjacency(G)
  laplace <- laplacian_matrix(m)
  v <- as.double(unlist(eigen(laplace)[2]))
  var <- sqrt(length(v))
  v <- matrix(v,var,var)[,2:k+1]
  return(v)
}