Processing 1.0 - Processing Discourse - Frequency count for values in a column?

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Frequency count for values in a column? (Read 572 times)

Dave_Li

Frequency count for values in a column?
Jan 29^th, 2010, 12:05am

Hi All,

I'm very new to Processing and am reading Fry's book Vizualizing Data, have finished reading until chap 4 and its been great so far. I'm applying it to a project and got into a difficulty recently..

In my tsv file, I have a column of data (student names) and I need to determine how many different unique values there are in that column (how many different students), and also, what is the frequency of each type of value (how many repetitions for each student name), preferrably get an output in an array format.

i.e. From:

Andy
Julie
Andy
Brad
Tom
Brad

To:

names [Andy, Julie, Brad, Tom]
freq [ 2, 1, 2, 1]

Does anyone know if the Table class featured in the book has any methods to accomplish this?

Or, if not, can anyone share if this is possible and how can it be done? Or is it explained somewhere in the later chapters of the book and I just need to read those chapters first?

Many thanks in advance!

Dave

PhiLho

Re: Frequency count for values in a column?
Reply #1 - Jan 29^th, 2010, 2:24am

Code:

String[] students =
{
  "Andy",
  "Julie",
  "Andy",
  "Brad",
  "Tom",
  "Brad"
};

HashMap stats = new HashMap();
for (int i = 0; i < students.length; i++)
{
  String student = students[i];
  Object o = stats.get(student);
  int nb = 0;
  if (o != null)
  {
    nb = (Integer) o;
  }
  stats.put(student, ++nb);
}
println(stats);

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