Sort text file data into an array

Question

I'm working on a homework problem for my computer science class. A cities census data is on a text file holding records for its citizens. Each line will have four fields(age, gender, marital status, and district) of different data types separated by a comma. For example, 22, F, M, 1.

How should I approach this? My thoughts are that I should use two 1D arrays, one for age and one for district. I need to be able to later count how many people are in each district, and how many people are in different age groups for the whole city.

How do I read each line and get the info I want into each array?

edit** This is what I've managed to do so far. I'm trying to separate my data from fields into four different arrays. This is where I'm stuck.

        FileStream fStream = new FileStream("test.txt", FileMode.Open, FileAccess.Read);
        StreamReader inFile = new StreamReader(fStream);

        string inputRecord = "";
        string[] fields;
        int[] ageData = new int[1000];
        string[] genderData = new string[1000];
        string[] maritalData = new string[1000];
        int[] districtData = new int[1000];



        inputRecord = inFile.ReadLine();
        while (inputRecord != null)
        {
            fields = inputRecord.Split(',');

            int i = 0;

            ageData[i] = int.Parse(fields[0]);
            genderData[i] = fields[1];
            maritalData[i] = fields[2];
            districtData[i] = int.Parse(fields[3]);
            i++;

            inputRecord = inFile.ReadLine();
         }

edit 2**

First question, I've decided to use the below code to find out how many citizens are in each district of the census data.

for (int x = 1; x <= 22; x++)
            for (int y = 0; y < districtData.Length; y++)
                if (districtData[y] == x)
                    countDist[x]++;

        for (int x = 1; x <= 22; x++)
            Console.WriteLine("District   " + x + "   has   " + countDist[x] + "   citizens");

In my .Writeline when x reaches two digits it throws off my columns. How could I line up my columns better?

Second question, I am not quite sure how to go about separating the values I have in ageData into age groups using an if statement.

Thank you for editing my original post from a block of text into something easier to read. — redcell98
– redcell98, Commented Mar 30, 2015 at 4:13

Eric J. · Accepted Answer · 2015-03-30 16:14:23Z

2

It sounds like each of the four fields have something in common... they represent a person surveyed by the census. That's a good time to use a class along the lines of

public class Person
{
    public int Age { get; set; }
    public string Gender { get; set; }
    public string MaritalStatus { get; set; }
    public int District { get; set; }
}

Then, just read in all of the lines from the text file (if it's small, it's fine to use File.ReadAllLines()), and then create an instance of Person for each line in the file.

You can create a

List<Person> people;

to hold the Person instances that you parse from the text file.

Since the lines appear to be separated by commas, have a look at String.Split().

UPDATE

The attempt in your edit is pretty close. You keep creating a new i and initializing it to 0. Instead, initialize it outside your loop:

int i = 0;
while (inputRecord != null)
{
    fields = inputRecord.Split(',');

Also you may want to trim excess spaces of of your input. If the fields are separated with ", " rather than just "," you will have excess spaces in your fields.

        genderData[i] = fields[1].Trim();
        maritalData[i] = fields[2].Trim();

edited Mar 30, 2015 at 16:14

answered Mar 30, 2015 at 3:19

Eric J.

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8 Comments

Xela Over a year ago

You can also use linq using this class structure, the linq below is a bit of an overkill though ;): List<Person> o = File.ReadAllLines(@"C:\TestCases\test.txt").Select(x => x.Split(',')).Select(y => new Person() { Age = int.Parse(y[0]), Gender = y[1], MaritalStatus = y[2], District = int.Parse(y[3]) }).OrderBy(y => y.Age).ToList();

redcell98 Over a year ago

Thank you for your comments to my question. We have not covered classes in class yet and your answers unfortunately are above what I understand

Eric J. Over a year ago

I honestly don't see why your professor would assign this question without having covered classes. I guess you could solve it with one List or array per attribute, but that would be a very bad structure and would teach a bad programming habit. What topics are you currently learning?

Eric J. Over a year ago

Just saw your edit... that's what was talking about with one array per attribute. What problem do you see exactly? (One problem: This will fail with more than 1000 lines in the file since your arrays are fixed at that size).

redcell98 Over a year ago

I am aware that this program will fail for more than 1000 lines. I have not decided if I should just make the number very large or if there is a better way. My concern right now is how I'm separating the data from fields[]. The only way I knew how to test it was a Console.WriteLine(ageData[0]); and then do another Console.WriteLine(ageData[1]); The first one displays the age of the last line of my file and the second give me a 0. So only one value is being saved into my array right now.

|

Xela · Accepted Answer · 2015-03-30 03:57:31Z

0

How about this?

List<string[]> o = File.ReadAllLines(@"C:\TestCases\test.txt").Select(x => x.Split(',')).OrderBy(y => y[0]).ToList();

Each person is a string array in the list. Each property is a index in the array eg: age is first. The above code reads all lines comma delimits them orders them by age and adds them to the list.

edited Mar 30, 2015 at 3:57

answered Mar 30, 2015 at 3:35

Xela

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1 Comment

redcell98 Over a year ago

Thank you for your comments to my question. We have not covered classes in class yet and your answers unfortunately are above what I understand.

Denys Vega · Accepted Answer · 2015-03-30 04:31:19Z

public static class PersonsManager
{
    public static PersonStatistics LoadFromFile(string filePath)
    {
        var statistics = new PersonStatistics();
        using (var reader = new StreamReader(filePath))
        {
            var separators = new[] { ',' };
            while (!reader.EndOfStream)
            {
                var line = reader.ReadLine();

                if (string.IsNullOrWhiteSpace(line))
                    continue; //--malformed line

                var lParts = line.Split(separators, StringSplitOptions.RemoveEmptyEntries);
                if (lParts.Length != 4)
                    continue; //--malformed line

                var person = new Person
                {
                    Age = int.Parse(lParts[0].Trim()),
                    Gender = lParts[1].Trim(),
                    MaritalStatus = lParts[2].Trim(),
                    District = int.Parse(lParts[3].Trim())
                };

                statistics.Persons.Add(person);
            }
        }

        return statistics;
    }
}

public class PersonStatistics
{
    public List<Person> Persons { get; private set; }

    public PersonStatistics()
    {
        Persons = new List<Person>();
    }

    public IEnumerable<Person> GetAllByGender(string gender)
    {
        return GetByPredicate(p => string.Equals(p.Gender, gender, StringComparison.InvariantCultureIgnoreCase));
    }

    //--NOTE: add defined queries as many as you need
    public IEnumerable<Person> GetByPredicate(Predicate<Person> predicate)
    {
        return Persons.Where(p => predicate(p)).ToArray();
    }
}

public class Person
{
    public int Age { get; set; }
    public string Gender { get; set; }
    public string MaritalStatus { get; set; }
    public int District { get; set; }
}

Usage:

var statistics = PersonsManager.LoadFromFile(@"d:\persons.txt");
var females = statistics.GetAllByGender("F");
foreach (var p in females)
{
    Console.WriteLine("{0} {1} {2} {3}", p.Age, p.Gender, p.MaritalStatus, p.District);
}

I hope it helps.

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