CODEWITHSUNDEEP
javasorting
adityak
adityak

Reputation: 192

sorting data in a file

I am facing a problem in sorting. The format of data is:

b4 S0_c5 t 0.426544 
b6 S1_c5 t 1.51049 
b13 S0_c5 t 0.594502 
b13 S1_c5 t 0.537496 
b15 S1_c5 t 0.884126   
b18 S0_c5 t 0.500933 
b19 S1_c5 t 0.628472 
b22 S0_c5 t 0.437718

and required result is:

S0_c5 b13 0.594502 b18 0.500933 b22 0.437718 b4 0.426544 
S1_c5 b6 1.51049 b15 0.884126 b19 0.628472 b13 0.537496

the value is also in descending order. Thanks in advance.

Upvotes: 1

Views: 213

Answers (5)

abhi
abhi

Reputation: 4792

Try this. It will work. 

private void ReadTextFile(String filename) throws IOException
    {
        BufferedReader br = null;
        FileInputStream fin = null;
        fin = new FileInputStream(filename);
        br =new BufferedReader(new InputStreamReader(fin));
        Map<String,String> stringStringMap = new TreeMap<String, String>(Collections.reverseOrder());
        while ((line = br.readLine()) != null) {
            stringStringMap.put(line.split(" ")[3],line);
        }
        Collection<String> collection = stringStringMap.values();
        Map<String, List<String>> map = new TreeMap<String, List<String>>();
        Iterator<String> iterator = collection.iterator();
        while(iterator.hasNext()){
            String[] tokens = iterator.next().split(" ");
            List<String> values = map.get(tokens[1]);
            if (values == null) {
                values = new ArrayList<String>();
                map.put(tokens[1], values);
            }
            values.add(tokens[0] + " " + tokens[3]);
        }
        for (List<String> mapList : map.values()) {
            Collections.sort(mapList);
        }
        for (String key : map.keySet()) {
            System.out.println(key + " " + map.get(key));
        }
    }

Upvotes: 1

tibtof
tibtof

Reputation: 7957

Put the data in a TreeList<String, List<String>> (because it's sorted) where the second word from a sequence is the key, and the value a list of strings, then sort each list you obtain this way:

    Map<String, List<String[]>> map = new TreeMap<String, List<String[]>>();
    for (String s : strings) {
        String[] tokens = s.split(" ");
        List<String[]> values = map.get(tokens[1]);
        if (values == null) {
            values = new ArrayList<String[]>();
            map.put(tokens[1], values);
        }
        values.add(new String[]{tokens[0],  tokens[3]});
    }

    for (String key : map.keySet()) {
        List<String[]> list = map.get(key);
        Collections.sort(list, new Comparator<String[]>() {

            @Override
            public int compare(String[] o1, String[] o2) {
                return o1[1].compareTo(o2[1]) * -1;
            }

        });

        System.out.print(key + " ");
        for (String[] s : list) {
            System.out.print(s[0] + " " + s[1]);
        }
        System.out.println();
    }

Update: E.g. to read from a file:

    BufferedReader br;
    try {
        br = new BufferedReader(new FileReader("d:/temp/r.res"));

        Map<String, List<String[]>> map = new TreeMap<String, List<String[]>>();
        while (br.ready()) {
            String s = br.readLine();
            if (!s.trim().isEmpty()) {
                String[] tokens = s.split(" ");
                List<String[]> values = map.get(tokens[1]);
                if (values == null) {
                    values = new ArrayList<String[]>();
                    map.put(tokens[1], values);
                }
                values.add(new String[]{tokens[0],  tokens[3]});
            }
        }
    } finally {
        br.close();
    }

Upvotes: 2

Christian Kuetbach
Christian Kuetbach

Reputation: 16060

  • Split your data by ' '.
  • Create a HashMap<String, List<String[]>>
  • For Each Row:
    • Look if the Map Contains the Key (split[1])
      • If there is no List at that key, create one
      • add split[1], split to the correct list
  • Iterate through your map and order each List
  • Output the data

Upvotes: 2

Vicky
Vicky

Reputation: 1235

there is a class in the JDK just for the purpose of having a sorted list. It is named (somewhat out of order with the other Sorted* interfaces) "java.util.PriorityQueue". It can sort either Comparables or using a Comparator.

The difference with a List sorted using Collections.sort(...) is that this will maintain order at all times, and have good insertion performance by using a heap data structure, where inserting in a sorted ArrayList will be O(n) (i.e., using binary search and move).

However other than List, PriorityQueue does not support indexed access (get(5)), the only way to access items in a heap is to take them out, one at a time (thus the name PriorityQueue).

Upvotes: 1

Francis Upton IV
Francis Upton IV

Reputation: 19443

Put the data into a List and use Collections.sort() to sort it.

Upvotes: 1

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