make_read.R

# Read ####

#' Making networks from external files
#'
#' @description 
#'   Researchers regularly need to work with a variety of external data formats.
#'   The following functions offer ways to import from some common external
#'   file formats into objects that `{manynet}` and other graph/network packages
#'   in R can work with:
#' 
#'   - `read_matrix()` imports adjacency matrices from Excel/csv files.
#'   - `read_edgelist()` imports edgelists from Excel/csv files.
#'   - `read_nodelist()` imports nodelists from Excel/csv files.
#'   - `read_pajek()` imports Pajek (.net or .paj) files.
#'   - `read_ucinet()` imports UCINET files from the header (.##h).
#'   - `read_dynetml()` imports DyNetML interchange format for rich social network data.
#'   - `read_graphml()` imports GraphML files.
#' @details
#'   Note that these functions are not as actively maintained as others
#'   in the package, so please let us know if any are not currently working
#'   for you or if there are missing import routines 
#'   by [raising an issue on Github](https://github.com/stocnet/manynet/issues).
#' @param file A character string with the system path to the file to import.
#'   If left unspecified, an OS-specific file picker is opened to help users select it.
#'   Note that in `read_ucinet()` the file path should be to the header file (.##h),
#'   if it exists and that it is currently not possible to import multiple
#'   networks from a single UCINET file. Please convert these one by one.
#' @param sv Allows users to specify whether their csv file is
#'   `"comma"` (English) or `"semi-colon"` (European) separated.
#' @param ... Additional parameters passed to the read/write function.
#' @return `read_edgelist()` and `read_nodelist()` will import
#'   into edgelist (tibble) format which can then be coerced or combined into
#'   different graph objects from there.
#'
#'   `read_pajek()` and `read_ucinet()` will import into
#'   a tidygraph format, since they already contain both edge and attribute data.
#'   `read_matrix()` will import into tidygraph format too.
#'   Note that all graphs can be easily coerced into other formats
#'   with `{manynet}`'s `as_` methods.
#' @family makes
#' @details There are a number of repositories for network data
#'   that hold various datasets in different formats. See for example:
#'
#'   - [UCINET data](https://sites.google.com/site/ucinetsoftware/datasets?authuser=0)
#'   - [Pajek data](http://vlado.fmf.uni-lj.si/pub/networks/data/)
#'   - [networkdata](https://schochastics.github.io/networkdata/)
#'   - [GML datasets](http://www-personal.umich.edu/~mejn/netdata/)
#'   - UCIrvine Network Data Repository
#'   - [KONECT project](http://konect.cc/)
#'   - [SNAP Stanford Large Network Dataset Collection](http://snap.stanford.edu/data/)
#'
#'   Please let us know if you identify any further repositories
#'   of social or political networks and we would be happy to add them here.
#'
#'   The `_ucinet` functions only work with relatively recent UCINET
#'   file formats, e.g. type 6406 files.
#'   To import earlier UCINET file types, you will need to update them first.
#'   To import multiple matrices packed into a single UCINET file,
#'   you will need to unpack them and convert them one by one.
#' @source 
#' `read_ucinet()` kindly supplied by Christian Steglich, 
#' constructed on 18 June 2015.
#' @importFrom utils read.csv read.csv2 read.table
#' @name read
#' @seealso [as]
NULL

#' @rdname read 
#' @export
read_matrix <- function(file = file.choose(),
                        sv = c("comma", "semi-colon"),
                        ...) {
  sv <- match.arg(sv)
  if (grepl("csv$", file)) {
    if (sv == "comma") {
      out <- read.csv(file, ...) # For US
    } else {
      out <- read.csv2(file, ...) # For EU
    }
  } else if (grepl("xlsx$|xls$", file)) {
    thisRequires("readxl")
    out <- readxl::read_excel(file, ...)
  }
  if((dim(out)[1]+1) == dim(out)[2])
    out <- out[,-1]
  if(!is.null(colnames(out)) & 
     all(colnames(out) == paste0("X",seq_along(colnames(out)))))
    colnames(out) <- NULL
  if(!is.null(colnames(out)) & is.null(rownames(out)) &
     dim(out)[1] == dim(out)[2])
    rownames(out) <- colnames(out)
  as_tidygraph(as.matrix(out))
}

#' @rdname read 
#' @export
read_edgelist <- function(file = file.choose(),
                          sv = c("comma", "semi-colon"),
                          ...) {
  sv <- match.arg(sv)
  if (grepl("csv$", file)) {
    if (sv == "comma") {
      out <- read.csv(file, header = TRUE, ...) # For US
    } else {
      out <- read.csv2(file, header = TRUE, ...) # For EU
    }
  } else if (grepl("xlsx$|xls$", file)) {
    thisRequires("readxl")
    out <- readxl::read_excel(file, ...)
  }
  out
}

#' @rdname read
#' @export
read_nodelist <- function(file = file.choose(),
                          sv = c("comma", "semi-colon"),
                          ...) {
  sv <- match.arg(sv)
  if (grepl("csv$", file)) {
    if (sv == "comma") {
      out <- read.csv(file, header = TRUE, ...) # For US
    } else {
      out <- read.csv2(file, header = TRUE, ...) # For EU
    }
  } else if (grepl("xlsx$|xls$", file)) {
    thisRequires("readxl")
    out <- readxl::read_excel(file, ...)
  }
  out
}

#' @rdname read
#' @param ties A character string indicating the ties/network,
#'   where the data contains several.
#' @importFrom network read.paj
#' @importFrom utils read.delim
#' @export
read_pajek <- function(file = file.choose(), 
                       ties = NULL,
                       ...) {
  paj <- network::read.paj(file, ...)
  if(!is.network(paj)){
    if(is.null(ties)) 
      stop(paste("This file contains multiple networks/ties.",
                 "Please choose a set of ties for the imported network among:\n",
                 paste0("- '", names(paj$networks), "'", collapse = "\n "),
                 "\n by adding the name as a character string to the `ties = ` argument"))
    out <- paj[[1]][[ties]]
    if("partitions" %in% names(paj)){
      for(x in names(paj$partitions)){
        out <- igraph::set_vertex_attr(out, name = gsub(".clu","",x),
                                       value = paj$partitions[,x])
      }
    }
    out <- as_tidygraph(out)
  } else {
    out <- as_tidygraph(paj)
  }
  # if(grepl("Partition", utils::read.delim(file))){
  #   clus <- strsplit(paste(utils::read.delim(file)), "\\*")[[1]]
  #   clus <- clus[grepl("^Vertices|^Partition", clus)][-1]
  #   if(length(clus) %% 2 != 0) stop("Unexpected .pajek file structure.")
  #   namo <- clus[c(TRUE, FALSE)]
  #   attr <- clus[c(FALSE, TRUE)]
  #   for (i in seq_len(namo)){
  #     vct <- strsplit(attr[i], ",")[[1]][-1]
  #     vct <- gsub("\"", "", vct)
  #     vct <- gsub(" ", "", vct, fixed = TRUE)
  #     vct <- vct[!grepl("^$", vct)]
  #     if(all(grepl("^-?[0-9.]+$", vct))) vct <- as.numeric(vct)
  #     out <- set_vertex_attr(out, name = strsplit(namo[i], " |\\.")[[1]][2], 
  #                            value = vct)
  #   }
  # } 
  out
}

#' @rdname read
#' @export
read_ucinet <- function(file = file.choose()) {
  # Some basic checks of the input file
  # Check if the file is a UCINET header file
  if (!grepl(".##h$", file)) {
    stop("Please select the UCINET header file with the
                                  '.##h' extension.")
  } # Continue if header file is selected
  # Check whether there is a data file to be imported in the same folder as the
  # hearder file.
  if (!(file.exists(sub("h$", "d", file)))) stop("UCINET data file not found.
                                                 Please add the '.##d' file in
                                                 the same folder as the header
                                                 file you are trying to
                                                 import. It should also have
                                                 the same name as the header
                                                 file.")
  read_ucinet_header <- function(header_file) {
    UCINET.header <- file(header_file, "rb")
    ignore <- readBin(UCINET.header, what = "int", size = 1)
    headerversion <- paste(
      rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
      rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
      rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
      rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
      rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
      sep = ""
    )
    # Check for correct UCINET version
    if (!(headerversion %in% c("DATE:", "V6404"))) {
      close(UCINET.header)
      stop(paste("Unknown header type; try more recent UCINET file types"))
    }
    # Get ymd and weekday of the UCINET file
    year <- 2000 + readBin(UCINET.header, what = "int", size = 2)
    month <- c(
      "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
      "Sep", "Oct", "Nov", "Dec"
    )[readBin(UCINET.header, what = "int", size = 2)]
    day <- readBin(UCINET.header, what = "int", size = 2)
    dow <- c(
      "Monday", "Tuesday", "Wednesday", "Thursday", "Friday",
      "Saturday", "Sunday"
    )[readBin(UCINET.header, what = "int", size = 2)]
    labtype <- readBin(UCINET.header, what = "int", size = 2)
    infile.dt <- c(
      "nodt", "bytedt", "booleandt", "shortintdt", "worddt",
      "smallintdt", "longintdt", "singledt", "realdt", "doubledt",
      "compdt", "extendeddt", "labeldt", "setdt", "stringdt", "pointerdt",
      "chardt", "integerdt", "nodelistdt", "sparsedt", "int64dt"
    )[
      readBin(UCINET.header, what = "int", size = 1)
    ]
    # Get the dimensions of the matrix
    ndim <- readBin(UCINET.header, what = "int", size = 2)
    if (headerversion == "V6404") {
      fct <- 2
    } else {
      fct <- 1
    }
    dims <- c(
      readBin(UCINET.header, what = "int", size = 2 * fct),
      readBin(UCINET.header, what = "int", size = 2 * fct)
    )
    if (ndim == 3) {
      dims[3] <- readBin(UCINET.header, what = "int", size = 2 * fct)
    }
    # Check if user tries to import multiple networks at once.
    # This check fails if it is a time series or multilevel network.
    if (!(ndim == 2 | ndim == 3 & dims[3] == 1)) {
      close(UCINET.header)
      stop(paste("UCINET file with", dims[3], "levels; please convert separately"))
    }
    # Extract the title of the UCINET network
    t.length <- readBin(UCINET.header, what = "int", size = 1)
    if (t.length > 0) {
      titl <- vapply(seq_len(t.length), function(i) {
        rawToChar(readBin(UCINET.header, what = "raw", size = 1))
      }, FUN.VALUE = character(1))
      titl <- paste(titl, collapse = "")
    } else {
      titl <- ""
    }
    haslab <- c(
      readBin(UCINET.header, what = "logical", size = 1),
      readBin(UCINET.header, what = "logical", size = 1)
    )
    if (ndim == 3) {
      haslab[3] <- readBin(UCINET.header, what = "logical", size = 1)
    }
    dim.labels <- list()
    for (arr.dim in seq_len(length(dims))) {
      if (haslab[arr.dim]) {
        dim.labels[[arr.dim]] <- rep(NA, dims[arr.dim])
        for (i in seq_len(dims[arr.dim])) {
          lab <- ""
          lablen <- readBin(UCINET.header, what = "int", size = 2)
          for (let in seq_len(lablen)) {
            lab <- paste(lab,
                         rawToChar(readBin(UCINET.header, what = "raw", size = 1)),
                         sep = ""
            )
          }
          dim.labels[[arr.dim]][i] <- lab
        }
      }
    }
    # Close file connection
    close(UCINET.header)
    if (ndim == 3 & dims[3] == 1) {
      titl <- dim.labels[[3]][1]
      # warning(paste('UCINET file with one level; level name "',
      # 	titl,'" treated as network name',sep=''))
      ndim <- 2
      dims <- dims[1:2]
      haslab <- haslab[1:2]
      dim.labels <- dim.labels[1:2]
    }
    return(list(
      headerversion = headerversion,
      date = paste(dow, paste(day, month, year, sep = "-")),
      labtype = labtype,
      infile.dt = infile.dt,
      ndim = ndim,
      dims = dims,
      titl = titl,
      haslab = haslab,
      dim.labels = dim.labels
    ))
  }
  # Start of main function code:
  header <- read_ucinet_header(file)
  file <- sub(".##h", "", file)
  # Read in the actual data file ".##d"
  UCINET.data <- file(paste(file, ".##d", sep = ""), "rb")
  thedata <- vector()
  for (i in 1:(header$dims[1] * header$dims[2])) {
    thedata[i] <- readBin(UCINET.data,
                          what = "numeric",
                          size = 4,
                          endian = "little"
    )
  }
  close(UCINET.data)
  # Build the adjacency matrix
  mat <- matrix(thedata,
                nrow = header$dims[2],
                ncol = header$dims[1],
                dimnames = header$dim.labels[c(2, 1)],
                byrow = TRUE
  )
  # put additional info from header file on matrix
  if (!(is.null(header$title))) {
    attr(mat, "title") <- header$title
  }
  attr(mat, "date") <- header$date
  # attr(mat,'labtype') <- header$labtype
  # attr(mat,'infile.dt') <- header$infile.dt
  # Convert the adjacency matrix to a tidygraph object
  as_tidygraph(mat)
}

#' @rdname read 
#' @importFrom dplyr bind_rows coalesce filter mutate select everything
#' @export
read_dynetml <- function(file = file.choose()) {
  thisRequires("xml2")
  name <- type <- nodeset <- target <- value <- NULL
  xmlfile <- xml2::read_xml(file)
  xmllist <- xml2::as_list(xmlfile)
  # Getting nodeset
  # to deal with legacy constructions:
  if("MetaMatrix" %in% names(xmllist$DynamicNetwork))
    nodesets <- xmllist$DynamicNetwork$MetaMatrix$nodes else
      nodesets <- xmllist$DynamicNetwork$MetaNetwork$nodes
  nodesets <- dplyr::coalesce(unlist(lapply(nodesets, 
                                            function(x) ifelse(is.null(attr(x, "id")),
                                                               NA_character_, attr(x, "id")))),
                              unlist(lapply(nodesets, 
                                            function(x) ifelse(is.null(attr(x, "type")),
                                                               NA_character_, attr(x, "type")))))
  # to deal with legacy constructions:
  if("MetaMatrix" %in% names(xmllist$DynamicNetwork)){
    nodesets <- unname(rep(nodesets, vapply(xmllist$DynamicNetwork$MetaMatrix$nodes,
                                            function(x) length(x), numeric(1))))
  } else
    nodesets <- unname(rep(nodesets, vapply(xmllist$DynamicNetwork$MetaNetwork$nodes,
                                            function(x) length(x), numeric(1)))) 
  # Getting nodes
  nodes <- xml2::as_list(xml2::xml_find_all(xmlfile, ".//node"))
  nodes <- dplyr::bind_rows(lapply(nodes, function(x){
    values <- sapply(x$properties, function(y) attr(y, "value"))
    attrs <- sapply(x$properties, function(y) attr(y, "name"))
    names(values) <- attrs
    c(name = attr(x, "id"), values)
  }))
  # Add nodeset information if necessary
  if(length(unique(nodesets))==2)
    nodes <- nodes %>% dplyr::mutate(type = nodesets == unique(nodesets)[2]) %>% 
    dplyr::select(name, type, dplyr::everything()) else if (length(unique(nodesets))>2)
      nodes <- nodes %>% dplyr::mutate(nodeset = nodesets) %>% 
    dplyr::select(name, nodeset, dplyr::everything())
  
  # Getting edges
  edgelist <- xml2::xml_attrs(xml2::xml_find_all(xmlfile, ".//edge"))
  # to deal with legacy constructions:
  if(length(edgelist)==0) edgelist <- xml2::xml_attrs(xml2::xml_find_all(xmlfile, ".//link"))
  edgelist <- as.data.frame(t(sapply(edgelist, function(x) x, simplify = TRUE)))
  edgelist$type <- NULL
  edgelist$value <- as.numeric(edgelist$value)
  edgelist <- dplyr::filter(edgelist, source %in% nodes$name & target %in% nodes$name)
  edgelist <- dplyr::filter(edgelist, value != 0)
  as_tidygraph(list(nodes = nodes, ties = edgelist))
}

#' @rdname read
#' @importFrom igraph read_graph
#' @export
read_graphml <- function(file = file.choose()) {
  as_tidygraph(igraph::read_graph(file, format = "graphml"))
}

# Write ####

#' Making networks to external files
#'
#' @description 
#'   Researchers may want to save or work with networks outside R.
#'   The following functions offer ways to export to some common external
#'   file formats:
#' 
#'   - `write_matrix()` exports an adjacency matrix to a .csv file.
#'   - `write_edgelist()` exports an edgelist to a .csv file.
#'   - `write_nodelist()` exports a nodelist to a .csv file.
#'   - `write_pajek()` exports Pajek .net files.
#'   - `write_ucinet()` exports a pair of UCINET files in V6404 file format (.##h, .##d).
#'   - `write_graphml()` exports GraphML files.
#' @details
#'   Note that these functions are not as actively maintained as others
#'   in the package, so please let us know if any are not currently working
#'   for you or if there are missing import routines 
#'   by [raising an issue on Github](https://github.com/stocnet/manynet/issues).
#' @inheritParams is
#' @param filename Character string filename.
#'   If missing, the files will have the same name as the object
#'   and be saved to the working directory.
#'   An appropriate extension will be added if not included.
#' @param name Character string to name the network internally, e.g. in UCINET.
#'   By default the name will be the same as the object.
#' @param ... Additional parameters passed to the write function.
#' @return The `write_`functions export to different file formats,
#'   depending on the function.
#' @family makes
#' @source 
#' `write_ucinet()` kindly supplied by Christian Steglich, 
#' constructed on 18 June 2015.
#' @importFrom utils write.csv write.csv2
#' @name write
#' @seealso [as]
NULL

#' @rdname write 
#' @export
write_matrix <- function(.data,
                         filename,
                         # name,
                         ...) {
  if (missing(.data)) {
    Abruzzo <- Campania <- Calabria <- Puglia <- NULL
    Abruzzo <- c(1, 0.76, 0.8, 0.90)
    Campania <- c(0.76, 1, 0.62, 0.69)
    Calabria <- c(0.80, 0.62, 1, 0.85)
    Puglia <- c(0.90, 0.69, 0.85, 1)
    out <- data.frame(Abruzzo, Campania, Calabria, Puglia)
    row.names(out)<- c('Abruzzo','Campania', 'Calabria', 'Puglia')
    out <- as_matrix(out)
    object_name <- "test"
  } else {
    object_name <- deparse(substitute(.data))
    out <- as_matrix(.data)
  }
  if (missing(filename)) filename <- paste0(getwd(), "/", object_name, ".csv")
  # if (missing(name)) name <- object_name
  write.csv(out, file = filename, row.names = FALSE)
}

#' @rdname write 
#' @export
write_edgelist <- function(.data,
                           filename,
                           # name,
                           ...) {
  if (missing(.data)) {
    out <- data.frame(
      from = c("A", "B", "C"),
      to = c("B", "C", "A"),
      weight = c(1.1, 11, 110)
    )
    object_name <- "test"
  } else {
    object_name <- deparse(substitute(.data))
    out <- as.data.frame(as_edgelist(.data))
  }
  if (missing(filename)) filename <- paste0(getwd(), "/", object_name, ".csv")
  # if (missing(name)) name <- object_name
  write.csv(out, file = filename, row.names = FALSE, ...)
}

#' @rdname write
#' @export
write_nodelist <- function(.data,
                           filename,
                           # name,
                           ...) {
  if (missing(.data)) {
    out <- data.frame(
      type = c(FALSE, FALSE, TRUE),
      name = c("A", "B", "C")
    )
    object_name <- "test"
  } else {
    object_name <- deparse(substitute(.data))
    out <- as.data.frame(as_tidygraph(.data))
  }
  if (missing(filename)) filename <- paste0(getwd(), "/", object_name, ".csv")
  # if (missing(name)) name <- object_name
  write.csv(out, file = filename, row.names = FALSE, ...)
}

#' @rdname write 
#' @importFrom igraph write_graph
#' @export
write_pajek <- function(.data,
                        filename,
                        ...) {
  if (missing(filename)) {
    object_name <- deparse(substitute(.data))
    filename <- paste0(getwd(), "/", object_name, ".net")
  }
  igraph::write_graph(as_igraph(.data),
                      file = filename,
                      format = "pajek",
                      ...
  )
}

#' @rdname write
#' @importFrom utils askYesNo
#' @return A pair of UCINET files in V6404 file format (.##h, .##d)
#' @export
write_ucinet <- function(.data,
                         filename,
                         name) {
  object_name <- deparse(substitute(.data))
  if (missing(filename)) filename <- paste0(getwd(), "/", object_name)
  if (missing(name)) name <- object_name
  # Check to avoid overwriting files by mistake
  if (file.exists(paste(filename, ".##h", sep = ""))) {
    overwrite <- utils::askYesNo(paste("There is already a file called ", 
                                       object_name, 
                                       ".##h here. Do you want to overwrite it?", 
                                       sep = ""))
    if (overwrite == FALSE | is.na(overwrite)) {
      stop("Writing aborted by user.")
    }
  }
  mat <- as_matrix(.data)
  # start with UCINET header file:
  UCINET.header <- file(paste(filename, ".##h", sep = ""), "wb")
  writeBin(as.integer(5), UCINET.header, size = 1)
  writeBin(charToRaw("V"), UCINET.header, size = 1)
  writeBin(charToRaw("6"), UCINET.header, size = 1)
  writeBin(charToRaw("4"), UCINET.header, size = 1)
  writeBin(charToRaw("0"), UCINET.header, size = 1)
  writeBin(charToRaw("4"), UCINET.header, size = 1)
  year <- as.integer(substr(Sys.Date(), 3, 4))
  writeBin(year, UCINET.header, size = 2)
  month <- as.integer(substr(Sys.Date(), 6, 7))
  writeBin(month, UCINET.header, size = 2)
  day <- as.integer(substr(Sys.Date(), 9, 10))
  writeBin(day, UCINET.header, size = 2)
  dow <- which(c(
    "Mon",
    "Tue",
    "Wed",
    "Thu",
    "Fri",
    "Sat",
    "Sun"
  ) == substr(date(), 1, 3))
  writeBin(dow, UCINET.header, size = 2)
  writeBin(as.integer(3), UCINET.header, size = 2)
  # labtype, unused in V6404 files
  writeBin(as.integer(7), UCINET.header, size = 1) # infile.dt = 7 'longintdt'
  writeBin(as.integer(2), UCINET.header, size = 2) # ndim = 2 for matrix
  writeBin(ncol(mat), UCINET.header, size = 4) # number of columns of matrix
  writeBin(nrow(mat), UCINET.header, size = 4) # number of rows of matrix
  writeBin(nchar(name), UCINET.header, size = 1) # length of matrix name
  if (nchar(name) > 0) {
    for (i in 1:nchar(name)) {
      writeBin(charToRaw(substr(name, i, i)), UCINET.header, size = 1)
    }
  }
  # Deal with column names of adjacency matrix
  labc <- colnames(mat)
  # Encoding(labc) <- "UTF-8"
  if (!is.null(labc)) {
    if (length(table(labc)) != length(labc)) {
      labc <- NULL
      warning("non-unique column labels, all column labels are dropped")
    }
  }
  writeBin(!is.null(labc), UCINET.header, size = 1)
  # Deal with column names of adjacency matrix
  labr <- rownames(mat)
  # Encoding(labr) <- "UTF-8"
  if (!is.null(labr)) {
    if (length(table(labr)) != length(labr)) {
      labr <- NULL
      warning("non-unique row labels, all row labels are dropped")
    }
  }
  writeBin(!is.null(labr), UCINET.header, size = 1)
  # Write node names of columns
  if (!is.null(labc)) {
    for (i in seq_len(ncol(mat))) {
      writeBin(as.integer(2 * nchar(labc[i])), UCINET.header, size = 2)
      for (let in seq_len(nchar(labc[i]))) {
        writeBin(charToRaw(substr(labc[i], let, let)),
                 UCINET.header,
                 size = 1
        )
        writeBin(raw(1), UCINET.header, size = 1)
      }
    }
  }
  # Write node names of rows
  if (!is.null(labr)) {
    for (i in seq_len(nrow(mat))) {
      writeBin(as.integer(2 * nchar(labr[i])), UCINET.header, size = 2)
      for (let in seq_len(nchar(labr[i]))) {
        writeBin(charToRaw(substr(labr[i], let, let)),
                 UCINET.header,
                 size = 1
        )
        writeBin(raw(1), UCINET.header, size = 1)
      }
    }
  }
  close(UCINET.header)
  # continue with UCINET data file: --> Write the actual matrix
  UCINET.data <- file(paste(filename, ".##d", sep = ""), "wb")
  for (i in seq_len(length(mat))) {
    writeBin(t(mat)[i], UCINET.data, size = 4, endian = "little")
  }
  close(UCINET.data)
}

#' @rdname write
#' @importFrom igraph write_graph
#' @export
write_graphml <- function(.data,
                          filename,
                          # name,
                          ...) {
  # if (missing(name)) name <- deparse(substitute(.data))
  if (missing(filename)) filename <- paste0(getwd(), "/", deparse(substitute(.data)), ".graphml")
  igraph::write_graph(.data,
                      filename,
                      format = "graphml")
}