;----------------------------------------------------------------------

; This example reads an ASCII file that is formatted a specific way, and

; writes out the results to a netCDF file.

;

; The first line in the ASCII file must be a header, with each field

; separated by a single character delimiter (like a ","). The rest of

; the file must be such that each row contains all fields, each

; separated by the designated delimiter.

;

; The fields can be integer, float, double, character, or string.

; String fields cannot be written to a netCDF file. They have to

; be read in as character arrays and written out that way.

;----------------------------------------------------------------------

;----------------------------------------------------------------------

; This function returns the index locations of the given delimiter

; in a row or several rows of strings.

;----------------------------------------------------------------------

function delim_indices(strings,nfields,delimiter)

local cstrings, cdelim

begin

  nrows = dimsizes(strings)

;

; Handle special case if we only have one string. Make sure it

; is put into a 2D array.

;

  if(nrows.eq.1) then

    cstrings = new((/1,strlen(strings)+1/),character)

  end if

  cstrings = stringtochar(strings)        ; Convert to characters.

  cdelim   = stringtochar(delimiter)      ; Convert delimiter to character.

;

; Som error checking here. Make sure delimiter is one character.

;

  nc   = dimsizes(cdelim)

  rank = dimsizes(nc)

  if(rank.ne.1.or.(rank.eq.1.and.nc.ne.2)) then

    print("delim_indices: fatal: the delimiter you've selected")

    print("must be a single character. Can't continue.")

    exit

  end if

;

; Create array to hold indices of delimiter locations, and then loop

; through each row and find all the delimiters. Make sure each row has

; the correct number of delimiters.

;

  ndelims  = nfields-1

  cindices = new((/nrows,ndelims/),integer)

  do i = 0, nrows-1

    ii = ind(cstrings(i,:).eq.cdelim(0))

;

; Make sure there were delimiters on this row. If not, we just quit.

; This could probably be modified to do this more gracefully.

;

    if(any(ismissing(ii))) then

      print("delim_indices: fatal: I didn't find any delimiters")

      print("('" + delimiter + "') on row " + i + ". Can't continue.")

      exit

    end if

    if(dimsizes(ii).ne.ndelims) then

      print("delim_indices: fatal: I expected to find " + ndelims)

      print("delimiters on row " + i + ". Instead, I found " + dimsizes(ii) + ".")

      print("Can't continue.")

      exit

    end if

    cindices(i,:) = ii

    delete(ii)            ; For next time through loop

  end do

  return(cindices)

end

;----------------------------------------------------------------------

; This function reads in a particular field from a string array,

; given the field number to read (fields start at #1 and go to #nfield),

; and the indices of the delimiters.

;

; It returns either an integer, float, double, character, or a string,

; depending on the input flag "return_type".

;----------------------------------------------------------------------

function read_field(strings,ifield,indices,return_type)

local nstring, cstrings, nf, tmp_str

begin

  nrows = dimsizes(strings)

;

; Handle special case if we only have one string. Make sure it

; is put into a 2D array.

;

  if(nrows.eq.1) then

    cstrings = new((/1,strlen(strings)+1/),character)

  end if

  cstrings = stringtochar(strings)

  nf       = dimsizes(indices(0,:))+1     ; indices is nrows x (nfields-1)

;

; Error checking. Make sure user has entered a valid field.

;

  if(ifield.le.0.or.ifield.gt.nf) then

    print("read_field: fatal: you've selected a field that is")

    print("out-of-range of the number of fields that you have (" + nf + ").")

    exit

  end if

;

; Set up array to return. For string, int, float, or double arrays,

; we don't have to do anything special. For character arrays,

; however, we do.

;

  if(return_type.ne."character") then

    return_array = new(nrows,return_type)

  else

;

; We don't know what the biggest character array is at this point, so

; make it bigger than necessary, and then resize later as necessary.

;

    tmp_return_array = new((/nrows,dimsizes(cstrings(0,:))/),"character")

    max_len = 0     ; Use to keep track of max lengths of strings.

  end if

  do i = 0,nrows-1

;

; Special case of first field in row.

;

    if(ifield.eq.1) then

      ibeg = 0

      iend = indices(i,ifield-1)-1

    else

;

; Special case of first field in row.

;

      if(ifield.eq.nf) then

        ibeg = indices(i,ifield-2)+1

        iend = dimsizes(cstrings(i,:))-1

;

; Any field between first and last field.

;

      else

        ibeg = indices(i,ifield-2)+1

        iend = indices(i,ifield-1)-1

      end if  

    end if

;

; Here's the code that pulls off the correct string, and converts it

; to float if desired.

;

    if(return_type.eq."integer") then

      return_array(i) = stringtointeger(chartostring(cstrings(i,ibeg:iend)))

    end if

    if(return_type.eq."float") then

      return_array(i) = stringtofloat(chartostring(cstrings(i,ibeg:iend)))

    end if

    if(return_type.eq."double") then

      return_array(i) = stringtodouble(chartostring(cstrings(i,ibeg:iend)))

    end if

    if(return_type.eq."string") then

      return_array(i) = chartostring(cstrings(i,ibeg:iend))

    end if

    if(return_type.eq."character") then

      if( (iend-ibeg+1) .gt. max_len) then

        max_len = iend-ibeg+1

      end if

      tmp_return_array(i,0:iend-ibeg) = cstrings(i,ibeg:iend)

    end if

  end do

  if(return_type.eq."character") then

    return_array = new((/nrows,max_len/),"character")

    return_array = tmp_return_array(:,0:max_len-1)

  end if

  return(return_array)

end

;----------------------------------------------------------------------

; This function reads in string fields only to get the maximum string

; length.

;----------------------------------------------------------------------

function get_maxlen(strings,ifield,indices)

local nstring, cstrings, nf, tmp_str

begin

  nrows = dimsizes(strings)

;

; Handle special case if we only have one string. Make sure it

; is put into a 2D array.

;

  if(nrows.eq.1) then

    cstrings = new((/1,strlen(strings)+1/),character)

  end if

  cstrings = stringtochar(strings)

  nf       = dimsizes(indices(0,:))+1     ; indices is nrows x (nfields-1)

;

; Error checking. Make sure user has entered a valid field.

;

  if(ifield.le.0.or.ifield.gt.nf) then

    print("read_field: fatal: you've selected a field that is")

    print("out-of-range of the number of fields that you have (" + nf + ").")

    exit

  end if

;

; We don't know what the biggest character array is at this point, so

; make it bigger than necessary, and then resize later as necessary.

;

  tmp_return_array = new((/nrows,dimsizes(cstrings(0,:))/),"character")

  max_len = 0     ; Use to keep track of max lengths of strings.

  do i = 0,nrows-1

;

; Special case of first field in row.

;

    if(ifield.eq.1) then

      ibeg = 0

      iend = indices(i,ifield-1)-1

    else

;

; Special case of first field in row.

;

      if(ifield.eq.nf) then

        ibeg = indices(i,ifield-2)+1

        iend = dimsizes(cstrings(i,:))-1

;

; Any field between first and last field.

;

      else

        ibeg = indices(i,ifield-2)+1

        iend = indices(i,ifield-1)-1

      end if  

    end if

    if( (iend-ibeg+1) .gt. max_len) then

      max_len = iend-ibeg+1

    end if

  end do

  return(max_len)

end

;----------------------------------------------------------------------

; Main code.

;----------------------------------------------------------------------

begin

;

; Set up defaults here.  We are hard-coding the field types here.

; You can set up this script to try to determine the field types 

; automatically, but this is a bit tedious. Maybe later.

;

  filename  = "data.933"                ; ASCII" file to read.

  cdf_file  = filename + ".nc"          ; netCDF file to write.

  nfields   = 45                        ; # of fields

  delimiter = ","                       ; field delimiter

;

; In this case, fields #6-#8 are strings, fields #2, #3, and #11

; are float, and the rest of the fields are integers.

;

  var_types      = new(nfields,string)

  var_strlens    = new(nfields,integer)   ; var to hold strlens, just in case.

  var_types      = "integer"       ; Most are ints.

  var_types(5:7) = "character"     ; Corresponds to fields 6-8.

  var_types(1:2) = "float"

  var_types(10)  = "float"

  if(isfilepresent(cdf_file))

    print("Warning: '" + cdf_file + "' exists. Will remove it.")

    system("/bin/rm " + cdf_file)

  end if

;

; Read in data as strings. This will create a string array that has the

; same number of strings as there are rows in the file. We will then need

; to parse each string later.

;

  read_data = asciiread(filename,-1,"string")

  header    = read_data(0)        ; Header. Use for variable names.

  data      = read_data(1:)       ; Get rid of first line which is a header.

  nrows     = dimsizes(data)      ; Number of rows.

;

; Read in locations of delimiters in each string row.

;

  hindices = delim_indices(header,nfields,delimiter)   ; header row

  dindices = delim_indices(data,nfields,delimiter)     ; rest of file

;

; Read in the field names which will become variable names on

; the netCDF file.

;

  var_names = new(nfields,string)

  do i=0,nfields-1

    var_names(i) = read_field(header,i+1,hindices,"string")

  end do

;

; Write out this netCDF file efficiently so it will be faster.

; Try to predefine everything before you write to it.

; 

  f = addfile(cdf_file,"c")

  setfileoption(f,"DefineMode",True)       ; Enter predefine phase.

;

; Write global attributes to file. It's okay to do this before 

; predefining the file's variables. We are still in "define" mode.

;

  fAtt               = True

  fAtt@description   = "Data read in from " + filename + " ASCII file."

  fAtt@creation_date = systemfunc ("date")        

  fileattdef( f, fAtt )        

;

; Write dimension names to file. If there are no character variables,

; then there's only one dimension name ("nvalues").

;

; Otherwise, we need to write a dimension name for every character

; variable, which will indicate the maximum string length for that

; variable.

;

  indc = ind(var_types.eq."character")

  if(.not.any(ismissing(indc))) then

;

; We have to treat the character arrays special here. We need to

; know their sizes so we can write the maximum size of each char

; array to the netCDF file as a dimension name. This means we

; need to read in the character variables once to get the string

; lengths, then we'll read them again later to get the actual values.

;

    do i=0,dimsizes(indc)-1

      var_strlens(indc(i)) = get_maxlen(data,indc(i)+1,dindices)

    end do

    ndims    = dimsizes(indc) + 1

    dimNames = new(ndims,string)

    dimSizes = new(ndims,integer)

    dimUnlim = new(ndims,logical)

    dimUnlim            = False

    dimUnlim(0)         = True

    dimNames(0)         = "nvalues"

    dimNames(1:ndims-1) = var_names(indc) + "_StrLen"

    dimSizes(0)         = -1

    dimSizes(1:ndims-1) = var_strlens(indc)

    filedimdef(f,dimNames,dimSizes,dimUnlim)

  else

;

; No character variables, so just write the one dimension name.

;

    filedimdef(f,"nvalues",-1,True)

  end if

;

; Define each variable on the file.

;

; Don't deal with variables that are of type string.

;

  do i=0,nfields-1

    if(var_types(i).ne."string") then

      if(var_types(i).ne."character") then

        filevardef(f, var_names(i), var_types(i), "nvalues")

      else

        filevardef(f, var_names(i), var_types(i),  \

                   (/"nvalues",var_names(i)+"_StrLen"/))

      end if

    end if

  end do

;

; Loop through each field, read the values for that field, print 

; information about the variable, and then write it to the netCDF

; file.

;

  do i=0,nfields-1

    ifield = i+1           ; Fields start at #1, not #0.

;

; Note: you can't write strings to a netCDF file, so these have

; to be written out as character arrays.

;

    tmp_data = read_field(data,ifield,dindices,var_types(i))

;

; Print some info about the variable.

;

    print("")

    print("Writing variable '" + var_names(i) + "' (field #" + ifield + ").")

    print("Type is " + var_types(i) + ".")

    if(var_types(i).ne."string".and.var_types(i).ne."character") then

      print("min/max = " + min(tmp_data) + "/" + max(tmp_data))

    end if

    if(any(ismissing(tmp_data))) then

      print("This variable does contain missing values.")

    else

      print("This variable doesn't contain missing values.")

    end if

    f->$var_names(i)$ = tmp_data       ; Write to netCDF file.

    delete(tmp_data)                   ; Delete for next round.

  end do

end