How to display unique numbers with their frequencies as occurring in a matrix?

Question

Hi . I have a matrice with some number:

1 2 3 6   
6 7 2 1   
1 4 5 6

And the program should display all different number with own frequency for example:

1 -> 3   
2 -> 2   
3 -> 1  
4 -> 1   
5 -> 1   
6 -> 3
7 -> 1

Please help me

Answer 1

You probably mean

1->3

Create vector (array), filled with zeros, that have size of max value in matrice (like [0..9]), travell by whole matrice and with every step increment index of vector that equals actual number.

This is soluction for short range values in matrice. If you excpect some big values, use joined list insted of vector, or matrice like this for counting:

1    0
5    0
15   0 
142  0
2412 0

And increment values in second column and expand this matrice rows every time you find a new number.

Answer 2

I have a random number in my matrice. How to do this . please help me

Answer 3

Using pointers this problem reduces from matrix to a single dimensional array. Maintain a 1D array whose size is equal to the total no. of elements in the matrix, say it COUNT. Initialize it with zero. Now start with first element of the matrix and compare it with all the other elements. If we use pointers this problem transforms into traversing a 1D array and finding the no of occurrences of each element. For traversing all you have to do is just increment the pointer. While comparing when you encounter the same number just shift forward all the consecutive numbers one place ahead. For example, if 0th element is 1 and you again found 1 on 4th index, then shift forward element on 5th index to 4th, 6th to 5th and so on till the last element. This way the duplicate entry at 4th index is lost. Now decrease the count of total no of elements in the matrix by 1 and increase the corresponding entry in array COUNT by 1. Continuing this way till the last element we get a matrix with distinct nos. and their corresponding frequency in array COUNT. This implementation is very effective for languages which support pointers.

Answer 4

Here's an example of how it could be done in Python. The dict is of this format: {key:value, key2:value2}. So you can use that so you have something like {'2':3} so it'll tell you what number has how many occurances. (I'm not assuming you're going to use Python. It's just so you understand the code... maybe)

matrix = [[1,5,6],
          [2,6,3],
          [5,3,9]]
dict = {}

for row in matrix:
    for column in row:
        if str(column) in dict.keys():
            dict[str(column)] += 1
        else:
            dict[str(column)] = 1

for key in sorted(dict.keys()):
    print key, '->', dict[key]

I hope you can figure out what this does. This codepad shows the output and nice syntax hightlighting.

(I don't get why SO isn't aligning the code properly... it's monospaced but not aligned :S ... turns out it's because I was using IE6 (It's the only browser at work :-(