Develop Reference

The sum for every column and raw in a 2D array with N columns

I have a 2D Array in C# with user input to fill the Array. I need help to find the sum for every column and row.
var input = Console.ReadLine();
var n = int.Parse(input);
int[,] intArr = new int[n, 3];
for (int i = 0; i < n; i++)
{
input = Console.ReadLine();
var parts = input.Split(' ');
for (int j = 0; j < 3; j++)
{
intArr[i, j] = int.Parse(parts[j]);
}
}
if (n == 1)
{
Console.WriteLine("Sum of column " + Convert.ToString(n) + ": " + (intArr[n - 1, 0] + intArr[n - 1, 1] + intArr[n - 1, 2]));
Console.WriteLine("Row1: " + (intArr[n - 1, 0]));
Console.WriteLine("Row2: " + (intArr[n - 1, 1]));
Console.WriteLine("Row3: " + (intArr[n - 1, 2]));
}
if (n == 2)
{
Console.WriteLine("Sum of column " + Convert.ToString(n - 1) + ": " + (intArr[n - 2, 0] + intArr[n - 2, 1] + intArr[n - 2, 2]));
Console.WriteLine("Sum of column " + Convert.ToString(n) + ": " + (intArr[n - 1, 0] + intArr[n - 1, 1] + intArr[n - 1, 2]));
Console.WriteLine("Row 1: " + (intArr[n - 2, 0] + intArr[n - 1, 0]));
Console.WriteLine("Row 2: " + (intArr[n - 2, 1] + intArr[n - 1, 1]));
Console.WriteLine("Row 3: " + (intArr[n - 1, 2] + intArr[n - 1, 1]));
}
}
User input:
2
1 2 3
4 5 6
The output:
Sum of column 1: 6
Sum of column 2: 15
Row 1: 5
Row 2: 7
Row 3: 11
I want this output for N columns enter by user, but I am stuck!
Thank you!

Not sure, is your problem that you get an undesired result or that you have a model with a fixed number of elements? An array is a fixed size data container, so if you want any number of columns the architecture perhaps is where you want to change away from array.
Anyway, problem 1 is that you let user chose how many rows they want, but now how many column, so presuming there will be 3 conflicts with you data. So you have on array the .getUpperBound() for that which takes a range parameter and this way we can use a dynamic strucure
//From:
for (int i = 0; i < n; i++)
{
input = Console.ReadLine();
var parts = input.Split(' ');
for (int j = 0; j < 3; j++)
{
intArr[i, j] = int.Parse(parts[j]);
}
}
//TO:
var rows = new List<int[]>();
for (int i = 0; i < n; i++)
{
input = Console.ReadLine();
var parts = input.Split(' ');
var listOf = new List<int>();
for (int j = 0; j < parts.GetUpperBound(0); j++)
{
listOf.Add(int.Parse(parts[j]));
}
rows.Add(listOf.ToArray());
}
from https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.aggregate?view=net-5.0 You get the aggregation capability
[Fact]
public void SumExerciseTest()
{
/*
The output:
Sum of column 1: 6
Sum of column 2: 15
Row 1: 5
Row 2: 7
Row 3: 11 => 9
*/
var testData = new[] { "1 2 3", "4 5 6" };
var input = "2"; // Console.ReadLine();
var n = int.Parse(input);
var rows = new List<int[]>(n);
for (int i = 0; i < n; i++)
{
input = testData[i];
var parts = input.Split(' ');
var listOf = new List<int>();
for (int j = 0; j <= parts.GetUpperBound(0); j++)
{
listOf.Add(int.Parse(parts[j]));
}
rows.Add(listOf.ToArray());
}
var rowSums = new List<int>(n);
foreach (int[] row in rows)
{
rowSums.Add(row.Aggregate((result, item) => result + item));
}
int maxLength = 0;
var rowLengths = new List<int>(n);
foreach (int[] row in rows)
{
rowLengths.Add(row.Length);
}
maxLength = rowLengths.Max();
int[] columnSums = new int[maxLength];
for (int idx = 0; idx < columnSums.Length; idx++){
foreach (var row in rows)
{
if (row.GetUpperBound(0) >= idx)
{
columnSums[idx] += row[idx];
}
}
}
int counter = 0;
//Outputting:
foreach(var sum in rowSums)
{
counter += 1;
System.Diagnostics.Debug.WriteLine($"Row {counter}: {sum}");
}
counter = 0;
foreach(var sum in columnSums)
{
counter += 1;
System.Diagnostics.Debug.WriteLine($"Column {counter}: {sum}");
}

Well, let's implement (extract) methods for summing arbitrary column and row:
private static int SumColumn(int[,] array, int column) {
if (array == null)
throw new ArgumentNullException(nameof(array));
if (column < 0 || column >= array.GetLength(1))
throw new ArgumentOutOfRangeException(nameof(column));
int result = 0;
for (int r = 0; r < array.GetLength(0); ++r)
result += array[r, column];
return result;
}
private static int SumRow(int[,] array, int row) {
if (array == null)
throw new ArgumentNullException(nameof(array));
if (row < 0 || row >= array.GetLength(0))
throw new ArgumentOutOfRangeException(nameof(row));
int result = 0;
for (int c = 0; c < array.GetLength(1); ++c)
result += array[row, c];
return result;
}
then you can put
for (int c = 0; c < intArr.GetLength(1); ++c)
Console.WriteLine($" Sum of column {c + 1}: {SumColumn(intArr, c)}");
for (int r = 0; r < intArr.GetLength(0); ++r)
Console.WriteLine($" Sum of row {r + 1}: {SumRow(intArr, r)}");

"rotate" values in array clockwise

Firstly thank you for taking the time to look at my question.
I have a csv file of letters for which i need to get the last letter of the array and move it to the start while "pushing" the other letters across
E.G.
--Source--
a,b,c,d,[e]
--Rotated--
e,a,b,c,d
for (var i = 0; i < Array.Length - 1; i++)
{
temp = Array[Array.Length];
Array[Array.Length] = Array[Array.Length - 1];
Array[i + 1] = Array[i];
Array[i] = temp;
}
For this I am aware that not all characters would be effected but i cant think of a loop to get all values moved

Use Copy method:
int last = arr[arr.Length - 1];
Array.Copy(arr, 0, arr, 1, arr.Length - 1);
arr[0] = last;

You can shift the numbers to right by using the modulo % operator :
int[] arr = { 1, 2, 3, 4, 5 };
int[] newArr = new int[arr.Length];
for (int i = 0; i < arr.Length; i++)
{
newArr[(i + 1) % newArr.Length] = arr[i];
}
newArr = {5,1,2,3,4}
DEMO HERE
EDIT:
Or you could make a method that shifts the numbers in your initial array without the need for creating a new array. The method rightShiftArray takes two parameters, the initial array arr an the number of shifts (shift) you want to perform:
public void rightShiftArray(ref int[] arr, int shift)
{
for (int i = 0; i < shift; i++)
{
int temp;
for (int j = 0; j < arr.Length - 1; j++)
{
temp = arr[j];
arr[j] = arr[arr.Length - 1];
arr[arr.Length - 1] = temp;
}
}
}
For example:
int[] arr = { 1, 2, 3, 4, 5 };
rightShiftArray(ref arr, 2);
The code above shifts the numbers in the initial array arr twice to the right and gives you the following output:
arr = { 4, 5, 1, 2, 3};
DEMO HERE

if you doesn't want to allocate new array, you can use this code :
newValue = Array[Array.Length-1];
for (var i = 0; i < Array.Length; i++)
{
temp = Array[i];
Array[i] = newValue;
newValue = temp;
}

Initialize 2 dimensional array inside nested loop

I am working on an issue where i need to Declare a two - dimensional array named multiplicationTable
that contains 4 elements by 4 elements.Initialize it in
a nested loop to contain elements that equal to the value
that is the product of the two index values for
each element. In a second nested loop, display the values
in the console output, with column elements separated with
commas, and row elements separated with carriage returns. This is what i have so far, for some reason can't wrap my brain around the solution! Any help would be appreciated!.
double[,] multiplicationTable = new double[4, 4];// { {1,2,3,4 }, {5,6,7,8 }, {9,10,11,12 }, {13,14,15,16 } };
for (int i = 0; i < multiplicationTable.GetLength(0); i++)
{
for (int j = 0; j < multiplicationTable.GetLength(1); j++)
{
double d = multiplicationTable[i, j];
if (j < multiplicationTable.GetLength(1) - 1)
{
Console.Write(d + ",");
}
else
{
Console.Write(d);
}
}
Console.Write("\n");
}
Console.ReadKey();

double[,] multiplicationTable = new double[4, 4];
for (int i = 0; i < multiplicationTable.GetLength(0); i++)
{
for (int j = 0; j < multiplicationTable.GetLength(1); j++)
{
multiplicationTable[i, j] = i * j;
double d = multiplicationTable[i, j];
if (j < multiplicationTable.GetLength(1) - 1)
{
Console.Write(d + ",");
}
else
{
Console.Write(d);
}
}
Console.Write("\n");
}
Console.ReadKey();

Why not try to solve this with String.Join method? It is easy to use and will save you a lot of if-else statements. Here it is how it will look like with this method:
double[,] multiplicationTable = new double[4, 4] { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 }, { 13, 14, 15, 16 } };
for (int i = 0; i < multiplicationTable.GetLength(0); i++)
{
var temp = new string[4];
for (int j = 0; j < multiplicationTable.GetLength(1); j++)
{
temp[j] = multiplicationTable[i, j].ToString();
}
Console.WriteLine(string.Join(",", temp));
}
Console.ReadKey();

double[,] multiplicationTable = new double[4, 4];
for (int i = 0; i < multiplicationTable.GetLength(0); i++)
{
var temp = new string[multiplicationTable.GetLength(0)];
for (int j = 0; j < multiplicationTable.GetLength(1); j++)
{
multiplicationTable[i, j] = i * j;
temp[j] = multiplicationTable[i, j].ToString();
}
Console.WriteLine(string.Join(",", temp));
}

A multidimensional array with systematic selected elements in C#

The wished output is a lot of array that looks like this:
public decimal [] array 1 = {1, 1, 0, 0, 0};
public decimal [] array 2 = {0, 1, 1, 0, 0};
public decimal [] array 3 = {0, 0, 1, 1, 0};
public decimal [] array 4 = {0, 0, 0, 1, 1};
The dimension does not fit my problem, because the problem demands a array of 14 elements, but the idear is the same. The question is how do I create this in a smart way. I tried a "for loop" creating array 1, but as the loop carried on it overwrote array 1 with array 2:
class Program
{
public decimal[] array_1 = { 0, 0, 0, 0, 0 };
public void Main(string[] args)
{
for (int i = 0; i < 5; i++)
{
if (i == 0)
{
array_1 [i] = 1;
array_1 [i + 1] = 1;
}
else if (i == 1)
{
array_1[i] = 1;
array_1[i + 1] = 1;
}
else if (i == 2)
{
array_1[i] = 1;
array_1[i + 1] = 1;
}
else if (i == 3)
{
array_1[i] = 1;
array_1[i + 1] = 1;
}
else if (i == 4)
{
array_1[i] = 1;
array_1[i + 1] = 1;
}
}
}
}
The output of the above is a array with only ones and not four different arrays as firstly wished.

decimal[][] arrays = { array_1, array_2, array_3, array_4 };
for (int a = 0; a < arrays.Length; a++) {
for (int i = 0; i < arrays[a].Length; i++) {
arrays[a][i] = i == a || i == a+1 ? 1 : 0;
}
}
Or, you can create one two-dimensional array:
decimal[,] array = new decimal[4, 5];
for (int row = 0; row < array.GetLength(0); row++) {
for (int column = 0; column < array.GetLength(1); column++) {
array[row, column] = column == row || column == row+1 ? 1 : 0;
}
}

Use multidimensional array:
class Program
{
public decimal[,] arrayObj = new decimal[5, 5];
public void Main(string[] args)
{
for (int i = 0; i < 4; i++)
{
arrayObj[i][i] = 1;
arrayObj[i+1] = 1;
}
}

If you want a collection (say, decimal[][] - jagged array) of arrays, I suggest using Linq:
int n = 4;
decimal[][] arrays = Enumerable.Range(1, n)
.Select(index => Enumerable
.Range(1, n + 1)
.Select(x => (decimal) (x == index || x == index + 1 ? 1 : 0))
.ToArray())
.ToArray();
and then use the collection
decimal array1 = arrays[0];
Test
string report = string.Join(Environment.NewLine, arrays
.Select(array => string.Join(" ", array)));
Outcome:
1 1 0 0 0
0 1 1 0 0
0 0 1 1 0
0 0 0 1 1
If you insist on 2d array:
int n = 4;
decimal[,] arrays = new decimal[n, n + 1];
for (int i = 0; i < arrays.GetLength(0); ++i) {
arrays[i, i] = 1;
arrays[i, i + 1] = 1;
}

Replacing two consecutive cell in an array with one cell

I was just asking if there is a simple way of doing this.
i.e. Replacing two consecutive cell with one cell having different value.
For ex: - if my array =[0,3,1,2,3,4], and i want to replace index 0,and 1 with the value 5
to become like this array=[5,1,2,3,4]
Can you guys suggest some simple way for doing this.
i do this code but there is something wrong:
int J = 0;
if (max != 1)
{
for (int iii = 0; iii < output.Length -1; iii++)
{
if ((output[iii] == imax) && (output[iii + 1] == jmax))
{
temp = temp + 1;
output[J] = Convert.ToByte(temp);
J = J + 1;
iii = iii + 1;
}
else
{
output[J] = output[iii];
J = J + 1;
output[J] = output[iii + 1];
}
}
}
because when i want to check the 2 consecutive index ,i want to pass them to the anther 2 index

If you care about performance you want to do as little operations that can harm performance. Try this extension method:
public static int[] ReplaceConsecutiveCells(this int[] array, int startIndex, int replaceWith)
{
int[] targetArray = new int[array.Length - 1];
for (int i = 0; i < array.Length; i++)
{
if (i < startIndex)
{
targetArray[i] = array[i];
}
else if (i == startIndex)
{
targetArray[i] = replaceWith;
}
else if (i == startIndex + 1)
{
// no action
}
else
{
targetArray[i - 1] = array[i];
}
}
return targetArray;
}
Use it like this:
array = array.ReplaceConsecutiveCells(0, 5);

int[] array = new int[] { 0, 3, 1, 2, 3, 4 };
List<int> list = array.ToList();
list.RemoveRange(0,2);
list.Insert(0, 5);
array = list.ToArray();

Yet another variant
int[] array = new int[] { 0, 3, 1, 2, 3, 4 };
Array.Reverse(array);
Array.Resize(ref array, 5);
Array.Reverse(array);
array[0] = 5;

do
{
RNG_NXT =RNG +1;
for (int iii = 0; iii <Nold -1; iii++)
{
if ((output[iii] == imax) && (output[iii + 1] == jmax))
{
output[J] = Convert.ToByte(RNG_NXT);
J = J + 1;
iii = iii + 1;
}
else
{
output[J] = output[iii];
J = J + 1;
}
}
RNG++;
}
while( RNG < RNG_MAX) ;