Class: Dobjects::Dvector

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
ext/Dobjects/Dvector/dvector.c,
lib/Dobjects/Dvector_extras.rb,
ext/Dobjects/Dvector/dvector.c,
ext/Tioga/FigureMaker/figures.c

Overview

Dvectors are a specialized implementation of one-dimensional arrays of double precision floating point numbers. They are intended for use in applications needing efficient processing of large vectors of numeric data. Essentially any of the operations you might do with a 1D Ruby Array of numbers can also be done with a Dvector. Just like Arrays, Dvector indexing starts at 0. A negative index is assumed to be relative to the end of the vector—that is, an index of -1 indicates the last element of the vector, -2 is the next to last element in the vector, and so on. Element reference and element assignment are the same as for Arrays, allowing for (start,length) or (range) as well as for simple indexing. All of the other Array operations that make sense for a 1D array of numbers are also provided for Dvectors. For example, you can “fetch” or “fill” with Dvectors, but there is no “assoc” or “compact” for them since one looks for arrays as elements and the other looks for nil elements, neither of which are found in Dvectors.

In addition to the usual Array methods, there are a variety of others that operate on the contents of the entire vector without the use of explicit iterators. These routines are crucial for efficient processing of large vectors. For example, “vec.sqrt” will create a vector of square roots of entries in vec more efficiently than the semantically equivalent form “vec.collect { |x| sqrt(x) }”.

All of the numeric methods also have ‘bang’ versions that modify the contents of the vector in place; for example, “vec.sqrt!” is more efficient than “vec = vec.sqrt”. By providing implicit iterators and in-place modification, Dvectors make it possible to operate on large vectors of doubles in Ruby at speeds closely approaching a C implementation.

As a final example, for diehards only, say we have large vectors holding values of abundances of total helium (xhe), singly ionized helium (xhe1), and doubly ionized helium (xhe2). We’re missing the values for neutral helium, but that is just what’s left of total helium after you subtract the two ionized forms, so it is easy to compute it. Finally, we need to calculate the log of the abundance of neutral helium and store it in another vector (log_xhe0). If we don’t care about creating work for the garbage collector, we can simply do this

log_xhe0 = (xhe - xhe1 - xhe2).log10

This works, but it creates multiple temporary vectors for intermediate results. If, like me, you’re compulsive about efficiency, you can do the whole thing with no garbage created at all:

log_xhe0 = Dvector.new
log_xhe0.replace(xhe).sub!(xhe1).sub!(xhe2).log10!

This copies xhe to log_xhe0, subtracts xhe1 and xhe2 from log_xhe0 in place, and then takes the log, also in place. It’s not pretty, but it is efficient – use if needed.

Please report problems with the Dvector extension to the tioga-users at rubyforge.org mailing list. [Note: for N-dimensional arrays or arrays of complex numbers or integers as well as doubles, along with a variety of matrix operations, check out the NArray extension.]

Dvector now also prides itselfs with a _dump and a _load function, which means you can Marshal them.

Constant Summary collapse

FANCY_READ_DEFAULTS =

Dvector.fancy_read’s defaults options. See that function for more details

{ 
  'sep' => /\s+/,
  'comments' => /^\s*\#/,
  'skip_first' => 0,
  'index_col' => false,
  'headers' => nil, # not used for now.
  'default' => 0.0/0.0, # defaults to NaN
  'initial_size' => 5001,
  'remove_space' => true ,# removes spaces at the beginning of the lines
}
WRITE_DEFAULTS = 
{
  'sep' => "\t",
  'write_mode' => "a",
}

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Object

Class Method Details

.[](*args) ⇒ Object

Returns a new Dvector populated with the given objects.

Dvector.[]( 1, 2, 3, 4 )      -> a_dvector
Dvector[ 1, 2, 3, 4 ]         -> a_dvector



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# File 'ext/Dobjects/Dvector/dvector.c', line 146

static VALUE dvector_s_create(int argc, VALUE *argv, VALUE klass) {
   VALUE ary = make_new_dvector(klass, argc, argc);
   Dvector *d = Get_Dvector(ary);
   if (argc < 0) {
      rb_raise(rb_eArgError, "negative number of arguments");
   }
   ary_to_dvector(argv, argc, d->ptr);
   return ary;
}

._load ⇒ Object

.compute_formula(formula, a, modules = []) ⇒ Object

This function is a rudimentary formula computing stuff. Give it a text formula and an array of Dvectors (a), and it returns a Dvector with the result. The formula should contain the following;

column

represents the current element of the n th Dvector of the array

This is just a try, and should be implemented in C rather than in Ruby. But if you’re looking for simplicity, here you go ;-) !

modules are the modules you would wish the evaluator to include. This feature enables one to make sure custom functions are included



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# File 'lib/Dobjects/Dvector_extras.rb', line 221

def Dvector.compute_formula(formula, a, modules = []) # :doc:

  evaluator = MathEvaluator.new(formula, "column", modules)
  # if we reach this place, it means that there a no big syntax errors ;-)
  
  # we now need to inspect the array given, and make sure that there is
  # and transform it into a clean stuff (an array with only Dvectors and
  # nil elements).
  
  target = []
  last = nil
  a.each { |elem| 
    if elem.is_a? Dvector
      target << elem
      last = elem
    else
      target << nil
    end
  }
  
  raise "No Dvector found" unless last
  
  # we check all the vectors have the same length
  target.each {|x| 
    if x && x.length != last.length
      raise "Dvectors should have all the same length !" 
    end
  }
  
  res = Dvector.new
  
  last.each_index { |i|
    args = target.collect { |val| 
      if val
        val[i]
      else 
        nil
      end
    }
    # we add the index at the beginning:
    #         args.unshift(i) 
    # Commented out for simplicity
    
    # then we call the block:
    elem = evaluator.compute(args)
    res << elem
  }
  
  return res
end

.create_pm_cubic_interpolant ⇒ Object

.create_spline_interpolant ⇒ Object

.fancy_read(stream, cols = nil, opts = {}) ⇒ Object

This function is a wrapper for #fast_fancy_read that reflects the look-and-feel of #old_fancy_read

Raises:

  • (ArgumentError) 


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# File 'lib/Dobjects/Dvector_extras.rb', line 93

def Dvector.fancy_read(stream, cols = nil, opts = {}) # :doc:
  o = FANCY_READ_DEFAULTS.dup
  o.update(opts)

  if stream.is_a?(String)
    stream = File.open(stream)
  end
  raise ArgumentError.new("'stream' should have a gets method") unless 
    stream.respond_to? :gets
  
  o['sep'] = Regexp.new(o['sep']) unless o['sep'].is_a? Regexp
  
  res = Dvector.fast_fancy_read(stream, o)

  # Adding the index columns if necessary
  if o["index_col"] 
    res.unshift(Dvector.new(res[0].length) { |i| i})
  end

  if cols
    return cols.map {|i| res[i] }
  else
    return res
  end
end

.fast_fancy_read(stream, options) ⇒ Object

:call-seq: Dvector.fast_fancy_read(stream, options) => Array_of_Dvectors

Reads data from an IO stream (or anything that supports a gets method) and separate it into columns of data according to the options, a hash holding the following elements (compulsory, but you can use FANCY_READ_DEFAULTS): ‘sep’: a regular expression that separate the entries ‘comments’: any line matching this will be skipped ‘skip_first’: skips that many lines before reading anything ‘index_col’: if true, the first column returned contains the

number of the line read

‘remove_space’: whether to remove spaces at the beginning of a line. *This

option is currently not implemented !*

‘comment_out’: this should be an array into which the comments

will be dumped one by one.

‘default’: what to put when nothing was found but a number must be used

In addition to these options that control the output, here are a few others to tune memory allocation; these can strongly improve the performance (or make it worse if you wish):

‘initial_size’: the initial size of the memory buffers: if there

are not more lines than that, no additional memory allocation/copy
occurs.



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# File 'ext/Dobjects/Dvector/dvector.c', line 5654

static VALUE dvector_fast_fancy_read(VALUE self, VALUE stream, VALUE options)
{
  /* First, we read up options: */
  double def = rb_num2dbl(rb_hash_aref(options, 
               rb_str_new2("default")));
  int remove_space = RTEST(rb_hash_aref(options, 
          rb_str_new2("remove_space")));
//  int index_col = RTEST(rb_hash_aref(options, 
//             rb_str_new2("index_col")));
  long skip_first = FIX2LONG(rb_hash_aref(options, 
            rb_str_new2("skip_first")));
  VALUE sep = rb_hash_aref(options, rb_str_new2("sep"));
  VALUE comments = rb_hash_aref(options, rb_str_new2("comments"));
  VALUE comment_out = rb_hash_aref(options, rb_str_new2("comment_out"));

  /* Then, some various variables: */
  VALUE line;

  ID chomp_id = rb_intern("chomp!");
  ID gets_id = rb_intern("gets");
  long line_number = 0;

  /* 
     Now come the fun part - rudimentary vectors management

     TODO: if the stream provides functionality to get its total size,
     it could be interesting to estimate the total number of lines
     based on some small heuristics
   */
  int nb_vectors = 0;   /* The number of vectors currently created */
  int current_size = 10;  /* The number of slots available */
  double ** vectors = ALLOC_N(double *, current_size);
  long index = 0;   /* The current index in the vectors */
  /* The size available in the vectors */
  int allocated_size = 
    FIX2LONG(rb_hash_aref(options, rb_str_new2("initial_size"))); 


  int i;

  /* The return value */
  VALUE ary;

  /* We use a real gets so we can also use StringIO, for instance */
  while(RTEST(line = rb_funcall(stream, gets_id, 0))) {
    VALUE pre, post, match;
    const char * line_ptr;
    int col = 0;
    line_number++;
    /* Whether we should skip the line... */
    if(skip_first >= line_number)
      continue;

    /* We check for a blank line using isspace: */
    line_ptr = StringValueCStr(line);
    while(line_ptr && *line_ptr) {
      if(! isspace(*line_ptr))
  break;
      line_ptr++;
    }
    if(! *line_ptr)
      continue;     /* We found a blank line  */
    if(remove_space)    /* We replace the contents of the line  */
      line = rb_str_new2(line_ptr);

    /* ... or a comment line */
    if(RTEST(comments) && RTEST(rb_reg_match(comments, line))) {
      if(RTEST(comment_out))
  rb_ary_push(comment_out, line);
      continue;
    }

    /* Then, we remove the newline: */
    post = line;
    rb_funcall(post, chomp_id, 0);

    /* We iterate over the different portions between
       matches
    */
    while(RTEST(post)) {
      const char * a;
      char * b;
      if(RTEST(rb_reg_match(sep, post))) {
  match = rb_gv_get("$~");
  pre = rb_reg_match_pre(match);
  post = rb_reg_match_post(match);
      }
      else {
  pre = post;
  post = Qnil;
      }
      a = StringValueCStr(pre);
      double c = strtod(a, &b);
      if(b == a) 
  c = def;
      if(col >= nb_vectors) {
  nb_vectors++;
  /* We need to create a new vector */
  if(col >= current_size) { /* Increase the available size */
    current_size += 5;
    REALLOC_N(vectors, double * , current_size);
  }
  
  double * vals = vectors[col] = ALLOC_N(double, allocated_size);
  /* Filling it with the default value */
  for(i = 0; i < index; i++) {
    vals[i] = def;
  }
      }
      vectors[col][index] = c;
      col++;
    }
    /* Now, we finish the line */
    for(; col < nb_vectors; col++)
      vectors[col][index] = def;
    index++;
    /* Now, we reallocate memory if necessary */
    if(index >= allocated_size) {
      allocated_size *= 2;  /* We double the size */
      for(col = 0; col < nb_vectors; col++)
  REALLOC_N(vectors[col], double, allocated_size);
    }
  }
  /* Now, we make up the array */
  ary = rb_ary_new();
  for(i = 0; i < nb_vectors; i++) {
    /* We create a vector */
    rb_ary_store(ary, i, make_dvector_from_data(cDvector, index, vectors[i]));
    /* And free the memory */
    free(vectors[i]);
  }
  free(vectors);
  return ary;
}

.from_na(na) ⇒ Object

thanks to Dave MacMahon for from_na and to_na Create a Dvector from an NArray.



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# File 'lib/Dobjects/Dvector_extras.rb', line 64

def Dvector.from_na(na)
  _load([1, na.length, na.to_s].pack('CIa*'))
end

.is_a_dvector ⇒ Object

.linear_interpolate ⇒ Object

.max_of_many ⇒ Object

.min_of_many ⇒ Object

.old_fancy_read(stream, cols = nil, opts = {}) ⇒ Object

This function reads in stream (can an IO object or a String, in which case it represents the name of a file to be opened) the columns specified by cols and returns them. column 0 is the first column. If cols is nil, then fancy_read attempts to find all the columns in the file, while filling absent data with NaN.

opts is a hash for tuning the behavior of the reading. It can hold the following keys:

‘sep’

the record separator

‘comments’

a regular expression matching comment lines

‘skip_first’

how many lines to skip at the beginning of the file,

‘default’

the value taken for missing elements

‘index_col’

if set to true, the first column contains the indices of the elements (starting from 0 for first and so on)

Raises:

  • (ArgumentError) 


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# File 'lib/Dobjects/Dvector_extras.rb', line 135

def Dvector.old_fancy_read(stream, cols = nil, opts = {}) # :doc:
  # first, we turn the stream into a real IO stream
  if stream.is_a?(String)
    stream = File.open(stream)
  end
  raise ArgumentError.new("'stream' should have a gets method") unless 
    stream.respond_to? :gets
  
  # we take default options and override them with opts
  o = FANCY_READ_DEFAULTS.merge(opts)
  
  # strip off the first lines.
  while o["skip_first"] > 0
    stream.gets
    o["skip_first"] -= 1
  end

  # then, parsing the lines. We store the results in an array. We read up
  # all columns, regardless of what is asked (it doesn't slow that much
  # the process -- or does it ?)
  
  columns = []
  line_number = 0 # the number of the significant lines read so far
  
  while line = stream.gets
    next if line =~ o["comments"]
    next if line =~ /^\s*$/ # skip empty lines
    if o["remove_space"]
      line.gsub!(/^\s+/,'')
    end
  
    elements = line.split(o["sep"])
    # now, the fun: the actual reading.
    # we first turn this elements into floats:
    numbers = elements.collect do |s| 
      begin 
        a = Float(s)
      rescue
        o["default"]
      end
    end

    if numbers.size < columns.size 
      # we pad it with default values
      while numbers.size < columns.size
        numbers << o["default"]
      end
    else
      # in that case, we need to create new Dvectors to match the
      # size of numbers
      while columns.size < numbers.size
        columns << Dvector.new(line_number, o["default"]) 
      end
    end
    # now, we should have the same number of elements both
    # in numbers and in columns
    columns.size.times do |i|
      columns[i] << numbers[i]
    end
    # and it's done ;-) !

    line_number += 1
  end
  # Adding the index columns if necessary
  if o["index_col"] 
    columns.unshift(Dvector.new(columns[0].length) { |i| i})
  end

  return columns unless cols
  return cols.collect { |i| 
    columns[i]
  }
end

.pm_cubic_interpolate ⇒ Object

.read ⇒ Object

.read_columns ⇒ Object

.read_row ⇒ Object

.read_rows ⇒ Object

.spline_interpolate ⇒ Object

.write(file, cols, options = {}) ⇒ Object

Writes an array of Dvectors into a text file



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# File 'lib/Dobjects/Dvector_extras.rb', line 278

def Dvector.write(file, cols, options = {})
  ops = WRITE_DEFAULTS.update(options)
  if file.is_a?(String)
    file = File.open(file, ops["write_mode"])
  end 
  nb = cols.map {|d| d.size}.max # The number of lines
  nb.times do |i|
    file.puts(cols.map {|d| d[i].to_s }.join(ops["sep"]))
  end
end

Instance Method Details

#<< ⇒ Object

#<=> ⇒ Object

#[] ⇒ Object Also known as: slice

#[]= ⇒ Object

#_dump ⇒ Object

dvector marshalling

#abs ⇒ Object

numeric methods

#abs! ⇒ Object

#acos ⇒ Object

standard math functions

#acos! ⇒ Object

#acosh ⇒ Object

#acosh! ⇒ Object

#add ⇒ Object Also known as: +, plus

#add! ⇒ Object Also known as: plus!

#as_exponent_of ⇒ Object

#as_exponent_of! ⇒ Object

#asin ⇒ Object

#asin! ⇒ Object

#asinh ⇒ Object

#asinh! ⇒ Object

#at ⇒ Object

#atan ⇒ Object

#atan! ⇒ Object

#atan2 ⇒ Object

#atan2! ⇒ Object

#atanh ⇒ Object

#atanh! ⇒ Object

#bounds ⇒ Object

Returns the boundaries of a Dvector, that is [min, max]. It ignores

NaN and will complain if the Dvector contains only NaN.

 v = Dvector[0.0/0.0, 0.0/0.0, 1,2,4,5,9,0.0/0.0,0.1]
 v.bounds -> [0.1, 9]



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# File 'ext/Dobjects/Dvector/dvector.c', line 5539

static VALUE dvector_bounds(VALUE self)
{
  double min, max;
  VALUE ret;
  long len;
  double * data = Dvector_Data_for_Read(self, &len);
  /* skip all NaNs at the beginning */
  while(len-- > 0)
    if(!isnan(*data++))
       break;
  if(len>=0)
    {
      min = max = *(data-1);
      while(len-- > 0)
  {
    if(! isnan(*data))
      {
        if(*data < min)
    min = *data;
        if(*data > max)
    max = *data;
      }
    data++;
  }
      ret = rb_ary_new2(2);
      rb_ary_store(ret, 0, rb_float_new(min));
      rb_ary_store(ret, 1, rb_float_new(max));
      return ret;
    }
  else
    rb_raise(rb_eRuntimeError, 
       "bounds called on an array containing only NaN");
  return Qnil;
}

#ceil ⇒ Object

#ceil! ⇒ Object

#clean? ⇒ Boolean

Returns:

  • (Boolean)

#clear ⇒ Object

#collect ⇒ Object Also known as: map

#collect! ⇒ Object Also known as: map!

#collect2 ⇒ Object Also known as: map2

#collect2! ⇒ Object Also known as: map2!

#concat ⇒ Object

#convolve(kernel, middle) ⇒ Object

:call-seq:

vector.convolve(kernel, middle)

convolve applies a simple convolution to the vector using kernel centered at the point middle. (0 is the leftmost point of the kernel).



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# File 'ext/Dobjects/Dvector/dvector.c', line 5582

static VALUE dvector_convolve(VALUE self, VALUE kernel, VALUE middle)
{
  long len;
  const double * values = Dvector_Data_for_Read(self, &len);
  VALUE retval = dvector_new2(len,len);
  double * ret = Dvector_Data_for_Write(retval,NULL);
  long kernel_len;
  const double * ker = Dvector_Data_for_Read(kernel, &kernel_len);
  /* I guess */
  long mid = NUM2LONG(middle);
  if(mid > kernel_len)
    rb_raise(rb_eArgError, "middle should be within kernel's range");
  else
    {
      long i,j,k;
      for(i = 0; i < len; i++) 
  {
    double sum = 0, k_sum = 0;
    for(j = 0; j < kernel_len; j++) 
      {
        /* check that we are within the vector */
        k = i - mid + j;   /* The current index inside the vector */
        /* This code is equivalent to saying that the vector is
     prolongated until infinity with values at the boundaries
     -> no, obnoxious, I think. Simply don't take care
     of these points
     -> yes, finally ?
        */
        if( k < 0)
/*    continue; */
    k = 0;
        if( k >= len)
/*    continue; */
    k = len - 1;
        sum += ker[j] * values[k];
        k_sum += ker[j];
      }
    sum/= k_sum;
    ret[i] = sum;
  }
    }
  return retval;
}

#cos ⇒ Object

#cos! ⇒ Object

#cosh ⇒ Object

#cosh! ⇒ Object

#delete ⇒ Object

#delete_at ⇒ Object

#delete_if ⇒ Object

#dirty= ⇒ Object

#dirty? ⇒ Boolean Also known as: dirty

dirty flag related methods

Returns:

  • (Boolean)

#div ⇒ Object Also known as: /

#div! ⇒ Object

#dot ⇒ Object

#dup ⇒ Object

#each ⇒ Object

#each2 ⇒ Object

#each2_with_index ⇒ Object

#each3 ⇒ Object

#each3_with_index ⇒ Object

#each_index ⇒ Object

#each_with_index ⇒ Object

#empty? ⇒ Boolean

Returns:

  • (Boolean)

#eql? ⇒ Boolean Also known as: ==

Returns:

  • (Boolean)

#exp ⇒ Object

#exp! ⇒ Object

#exp10 ⇒ Object

#exp10! ⇒ Object

#extrema(*args) ⇒ Object

Returns a list of local extrema of the vector, organized thus:

[ [:min, idmin1], [:max, idmax1], ...]

The values are pushed in the order in which they are found. It works thus: it scans the vector and looks around the current point in a given window. If the current point is the maximum or the minimum, it is considered as a local maximum/minimum. Control over which extrema are included is given to the used through threshold mechanisms.

The options hash controls how the peaks are detected: window: the number of elements on which we look on

both sides (default 5, ie the local maximum is over 11 points)

threshold: the minimum amplitude the extrema must have to

be considered (default 0)

dthreshold: how much over/under the average an extremum must be

(default 0)

or: whether the threshold and dthreshold tests are both

necessary or if only one is (default false: both tests are
necessary)

Note:* beware of NANs ! They will screw up peak detection, as they are neither bigger nor smaller than anything…



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# File 'ext/Dobjects/Dvector/dvector.c', line 5814

static VALUE dvector_extrema(int argc, VALUE *argv, VALUE self)
{
  long window = 5;
  double threshold = 0;
  double dthreshold = 0;
  int inclusive = 1;
  
  if(argc == 1) {
    VALUE t;
    t = rb_hash_aref(argv[0], rb_str_new2("window"));
    if(RTEST(t)) {
      window = FIX2LONG(t);
    }
    t = rb_hash_aref(argv[0], rb_str_new2("threshold"));
    if(RTEST(t)) {
      threshold = rb_num2dbl(t);
    }
    t = rb_hash_aref(argv[0], rb_str_new2("dthreshold"));
    if(RTEST(t)) {
      dthreshold = rb_num2dbl(t);
    }
    
    t = rb_hash_aref(argv[0], rb_str_new2("or"));
    inclusive = ! RTEST(t);
  } else if(argc > 1)
    rb_raise(rb_eArgError, "Dvector.extrema only takes 0 or 1 argument");

  /* Handling of the vector */
  long len, i,j;
  double * data = Dvector_Data_for_Read(self, &len);
  VALUE s_min = ID2SYM(rb_intern("min"));
  VALUE s_max = ID2SYM(rb_intern("max"));

  

  VALUE ret = rb_ary_new();
           
  for(i = 0; i < len; i++) {

    /* This is stupid and will need decent optimization when I have
       time */
    long first = i > window ? i - window : 0;
    double cur_min = data[first];
    long cur_min_idx = first;
    double cur_max = data[first];
    long cur_max_idx = first;
    double average = 0;
    long nb = 0;
    
    for(j = first; (j < i+window) && (j < len); j++,nb++) {
      average += data[j];
      if(data[j] <= cur_min) {
  cur_min = data[j];
  cur_min_idx = j;
      }
      if(data[j] >= cur_max) {
  cur_max = data[j];
  cur_max_idx = j;
      }
    }
    average /= nb;

    if(cur_min_idx == i) {
      /* This is a potential minimum */
      if((inclusive && 
    (fabs(cur_min) >= threshold) && 
    (fabs(cur_min - average) >= dthreshold))
   || (!inclusive && 
       ((fabs(cur_min) >= threshold) ||
        (fabs(cur_min - average) >= dthreshold))
       )) {
  VALUE min = rb_ary_new();
  rb_ary_push(min, s_min);
  rb_ary_push(min, LONG2FIX(i));
  rb_ary_push(ret, min);
      }
    }
    else if(cur_max_idx == i) {
      /* A potential maximum */
      if((inclusive && 
    (fabs(cur_max) >= threshold) && 
    (fabs(cur_max - average) >= dthreshold))
   || (!inclusive && 
       ((fabs(cur_max) >= threshold) ||
        (fabs(cur_max - average) >= dthreshold))
       )) {
  VALUE max = rb_ary_new();
  rb_ary_push(max, s_max);
  rb_ary_push(max, LONG2FIX(i));
  rb_ary_push(ret, max);
      }
    }
  }
  return ret;
}

#fetch ⇒ Object

#fft! ⇒ Object

Performs an in-place Fourier transform of the vector. The results is stored in the so-called “half-complex” format (see www.fftw.org/fftw3_doc/The-Halfcomplex_002dformat-DFT.html for more information).



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# File 'ext/Dobjects/Dvector/dvector.c', line 5921

static VALUE dvector_fft(VALUE self)
{
  long len;
  double * values = Dvector_Data_for_Write(self, &len);
  fftw_plan plan = fftw_plan_r2r_1d(len, values, values,
            FFTW_R2HC, FFTW_ESTIMATE);
  fftw_execute(plan);
  fftw_destroy_plan(plan);
  return self;
}

#fft_conj! ⇒ Object

Converts the FFTed data in the complex conjugate



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# File 'ext/Dobjects/Dvector/dvector.c', line 5994

static VALUE dvector_fft_conj(VALUE self)
{
  long len;
  double * v1 = Dvector_Data_for_Write(self, &len);
  double * img;
  long i;
  for(i = 1, img = v1 + len-1; i < (len+1)/2;
      i++, img--)
    *img = -*img;
  return self;
}

#fft_mul!(m) ⇒ Object

Multiplies the FFTed data held in the vector by another vector. The behaviour depends on the size of the target vector:

if it is the same size, it is assumed to be FFTed data if it is the same size of a power spectrum, then it is assumed that it

is multiplication by real values

anything else won’t make this function happy.

As a side note, if you only want multiplication by a scalar, the standard #mul! should be what you look for.



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# File 'ext/Dobjects/Dvector/dvector.c', line 6019

static VALUE dvector_fft_mul(VALUE self, VALUE m)
{
  long len;
  double * v1 = Dvector_Data_for_Write(self, &len);
  long len2;
  const double * v2 = Dvector_Data_for_Write(m, &len2);
  if(len2 == len) {   /* Full complex multiplication */
    const double * m_img;
    const double * m_real;
    double * v_img;
    double * v_real;
    long i;
    /* First, special cases */
    v1[0] *= v2[0];
    if(len % 2 == 0)
      v1[len/2] *= v2[len/2];
    
    for(i = 1, m_real = v2 + 1, m_img = v2 + len-1,
    v_real = v1 + 1, v_img = v1 + len-1; i < (len+1)/2;
  i++, m_real++, v_real++, m_img--, v_img--) {
      double r = *m_real * *v_real - *m_img * *v_img;
      *v_img = *m_real * *v_img + *v_real * *m_img;
      *v_real = r;
    }
    return self;
  }
  else if(len2 == len/2+1) {    /* Complex * real*/
    const double * val;
    double * v_img;
    double * v_real;
    long i;
    /* First, special cases */
    v1[0] *= v2[0];
    if(len % 2 == 0)
      v1[len/2] *= v2[len/2];
    
    for(i = 1, val = v2 + 1,
    v_real = v1 + 1, v_img = v1 + len-1; i < (len+1)/2;
  i++, val++, v_real++, v_img--) {
      *v_real *= *val;
      *v_img *= *val;
    }
    return self;
  }
  else {
    rb_raise(rb_eArgError, "incorrect Dvector size for fft_mul!");
  }
}

#fft_spectrum ⇒ Object

Returns the power spectra of the ffted data (ie the square of the norm of the complex fourier coefficients.

The returned value is a new Dvector of size about two times smaller than the original (precisely size/2 + 1)

For some reasons, convolutions don’t work for now.



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# File 'ext/Dobjects/Dvector/dvector.c', line 5966

static VALUE dvector_fft_spectrum(VALUE self)
{
  long len;
  const double * values = Dvector_Data_for_Read(self, &len);
  /* First compute the size of the target: */
  long target_size = len/2+1;
  long i;
  VALUE retval = dvector_new2(target_size,target_size);
  double * ret = Dvector_Data_for_Write(retval,NULL);

  /* Pointer to real and imaginary parts */
  const double * real;
  const double * img;
  ret[0] = values[0] * values[0];


  /* The Nyquist frequency */
  if(len % 2 == 0)
    ret[target_size - 1] = values[target_size-1] * values[target_size-1];
  for(i = 1, real = values + 1, img = values + len-1; i < len/2;
      i++, real++, img--)
    ret[i] = *real * *real + *img * *img;
  return retval;
}

#fill ⇒ Object

#first ⇒ Object

#floor ⇒ Object

#floor! ⇒ Object

#freeze ⇒ Object

#frozen? ⇒ Boolean

Returns:

  • (Boolean)

#include? ⇒ Boolean

Returns:

  • (Boolean)

#index ⇒ Object

#initialize_copy ⇒ Object

#insert ⇒ Object

#inv ⇒ Object

#inv! ⇒ Object

#join ⇒ Object

#last ⇒ Object

#length ⇒ Object Also known as: size, nitems

#log ⇒ Object

#log! ⇒ Object

#log10 ⇒ Object

#log10! ⇒ Object

#make_bezier_control_points_for_cubic_in_x ⇒ Object

#max ⇒ Object

#max_lt ⇒ Object

#min ⇒ Object

#min_gt ⇒ Object

#modulo ⇒ Object Also known as: mod, %

#modulo! ⇒ Object Also known as: mod!

#mul ⇒ Object Also known as: *, times

#mul! ⇒ Object Also known as: times!

#neg ⇒ Object Also known as: -@

nonstandard math functions

#neg! ⇒ Object

#pop ⇒ Object

#pow ⇒ Object Also known as: raised_to, **

#pow! ⇒ Object Also known as: raised_to!

#prune ⇒ Object

#prune! ⇒ Object

#push ⇒ Object

#reject ⇒ Object

#reject! ⇒ Object

#remainder ⇒ Object

#remainder! ⇒ Object

#replace ⇒ Object

#resize ⇒ Object

#reverse ⇒ Object

#reverse! ⇒ Object

#reverse_each ⇒ Object

#reverse_each2 ⇒ Object

#reverse_each2_with_index ⇒ Object

#reverse_each3 ⇒ Object

#reverse_each3_with_index ⇒ Object

#reverse_each_index ⇒ Object

#reverse_each_with_index ⇒ Object

#rfft! ⇒ Object

Performs a reverse in-place Fourier transform of the vector. The original data must have been stored in the so called “half-complex” format (see #fft!).



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# File 'ext/Dobjects/Dvector/dvector.c', line 5938

static VALUE dvector_rfft(VALUE self)
{
  long len;
  double * values = Dvector_Data_for_Write(self, &len);
  fftw_plan plan = fftw_plan_r2r_1d(len, values, values,
            FFTW_HC2R, FFTW_ESTIMATE);
  fftw_execute(plan);
  fftw_destroy_plan(plan);
  return self;
}

#rindex ⇒ Object

#round ⇒ Object

#round! ⇒ Object

#safe_acos ⇒ Object

#safe_acos! ⇒ Object

#safe_asin ⇒ Object

#safe_asin! ⇒ Object

#safe_inv ⇒ Object

#safe_inv! ⇒ Object

#safe_log ⇒ Object

#safe_log! ⇒ Object

#safe_log10 ⇒ Object

#safe_log10! ⇒ Object

#safe_sqrt ⇒ Object

#safe_sqrt! ⇒ Object

#select ⇒ Object

#set ⇒ Object

#shift ⇒ Object

#sin ⇒ Object

#sin! ⇒ Object

#sinh ⇒ Object

#sinh! ⇒ Object

#slice! ⇒ Object

#sort ⇒ Object

#sort! ⇒ Object

#sqrt ⇒ Object

#sqrt! ⇒ Object

#sub ⇒ Object Also known as: -, minus

#sub! ⇒ Object Also known as: minus!

#sum ⇒ Object

#tan ⇒ Object

#tan! ⇒ Object

#tanh ⇒ Object

#tanh! ⇒ Object

#to_a ⇒ Object Also known as: to_ary

#to_dvector ⇒ Object 



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# File 'lib/Dobjects/Dvector_extras.rb', line 74

def to_dvector
  self
end

#to_na ⇒ Object

Create an NArray with the same length and contents as self.



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# File 'lib/Dobjects/Dvector_extras.rb', line 69

def to_na
  ::NArray.to_na(_dump(nil)[5..-1], ::NArray::DFLOAT)
end

#to_s ⇒ Object Also known as: inspect

#tridag ⇒ Object

#trim ⇒ Object

#trim! ⇒ Object

#uniq ⇒ Object

#uniq! ⇒ Object

#unshift ⇒ Object

#values_at ⇒ Object

#vector_length ⇒ Object

#where_closest ⇒ Object Also known as: where_first_closest

#where_first_eq ⇒ Object Also known as: where_eq

#where_first_ge ⇒ Object Also known as: where_ge

#where_first_gt ⇒ Object Also known as: where_gt

#where_first_le ⇒ Object Also known as: where_le

#where_first_lt ⇒ Object Also known as: where_lt

#where_first_ne ⇒ Object Also known as: where_ne

#where_last_closest ⇒ Object

#where_last_eq ⇒ Object

#where_last_ge ⇒ Object

#where_last_gt ⇒ Object

#where_last_le ⇒ Object

#where_last_lt ⇒ Object

#where_last_max ⇒ Object

#where_last_min ⇒ Object

#where_last_ne ⇒ Object

#where_max ⇒ Object Also known as: where_first_max

#where_min ⇒ Object Also known as: where_first_min