Loop over a matrix

In your workspace, there's a matrix ttt, that represents the status of a tic-tac-toe game. It contains the values "X", "O" and "NA". Print out ttt to get a closer look. On row 1 and column 1, there's "O", while on row 3 and column 2 there's "NA".

To solve this exercise, you'll need a for loop inside a for loop, often called a nested loop. Doing this in R is a breeze! Simply use the following recipe:

for (var1 in seq1) {
  for (var2 in seq2) {
    expr
  }
}

This is a part of the course

“Intermediate R”

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Exercise instructions

Finish the nested for loops to go over the elements in ttt:

The outer loop should loop over the rows, with loop index i (use 1:nrow(ttt)).
The inner loop should loop over the columns, with loop index j (use 1:ncol(ttt)).
Inside the inner loop, make use of print() and paste() to print out information in the following format: "On row i and column j the board contains x", where x is the value on that position.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# The tic-tac-toe matrix ttt has already been defined for you

# define the double for loop
for (___ in ___) {
  for (___ in ___) {
    print(___)
  }
}

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