Append to a file#

We could use the File.append function to append our new data to the end of our file. The syntax of this command is similar:

Appending to a file

File.append("string", "path/to/file");

Let's try this.

Make a new script that uses append to add new strings to our file.

file_name = "path/file_name.txt";
File.append("string", file_name);

Try appending a few different things to the file.

What happens when we try to append a string to a file that does not exist?

Just like the print command we saw earlier, ImageJ will create the file.

Update your script so that it uses File.append to write our coordnates to a file. Make sure that it prints in the form x-coordinate, y-coordinate for each pair of coordinates

macro "get_mouse_xy [g]" {
  file_name = "path/to/file.txt";
  getCursorLoc(x, y, z, modifiers);
  File.append(x + "," + y, file_name);

  if (getSliceNumber + 1 < nSlices) {
      setSlice(getSliceNumber + 1);
  }
}

Try opening our data in excel. You will have to tell excel that the file is delimited by the , symbol.

Bonus exercise#

Add a header to the columns in our file. Hint: We will need to do something just after our file is created for the first time. How can we know if our file has just been created? Take a look at the documentation for the File functions and see if something might work?

macro "get_mouse_xy [g]" {
  file_name = "path/test_track.txt";

  if (!File.exists(file_name)) {
    File.append("X, Y", file_name); // (1)!
  } else {
    getCursorLoc(x, y, z, modifiers);
    File.append(x + "," + y, file_name);
  }

  if (getSliceNumber + 1 < nSlices) {
    setSlice(getSliceNumber + 1);
  }
}

Even if you didn't get to this answer, take a look at it and try to understand what's going on. How are we finding out of the file is newly created?