给定两个数组，如何遍历一个数组并推入第二个数组的重复元素？

Question

I'm writing a google apps script to take in a sheet with rows:

StudentName, StudentID, Gender, CoursePreference1, CoursePreference2, CoursePreference 3

and outputting:

StudentName, StudentID, Gender, CoursePreference1
StudentName, StudentID, Gender, CoursePreference2
StudentName, StudentID, Gender, CoursePreference3

I'm transforming the format so that instead of having one row per student with a column for each of their preferences, I'll have a row for each course preference with repeated student information.

I've tried to use other answers with nested for loops and the map method to get to where I'm going, but I'm completely tied in knots.

The first half of my code setting up two arrays works fine; each element of studentInfo is intended to be repeated for each element of the associated index of courseInfo:

function requestFileConversion() {

  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var input = ss.getSheetByName('Input');
  var output = ss.getSheetByName("Output");

  output.getRange('A2:I').clearContent();
  output.getRange('A2:I').setNumberFormat('@STRING@');

  var studentInfo = input.getRange(2, 1, input.getLastRow() - 1, 8).getValues();
  var courseInfo = input.getRange(2, 9, input.getLastRow() - 1, 23).getValues();

  var appendValues = [];

then the second half is where I've broken down; my completely non-functional attempt looks like this:

 for (var i=0; i < courseInfo.length; i++) {
    var requestCollection = [];
    for (var j=0; j < courseInfo[i].length; j++) {
      requestCollection.push(studentInfo[i] + courseInfo[j]);
    };

if (requestCollection.length > 0) {
Array.prototype.push.apply(appendValues, requestCollection);
};
};

The desired results of the transformation is to go from a set of rows in the form:

Jenny, id100, F, English, Science, Math, Physics
Johnny, id101, M, Science, Sports, Gym, English

and produce:

Jenny, id100, F, English
Jenny, id100, F, Science
Jenny, id100, F, Math
Jenny, id100, F, Physics
Johnny, id101, M, Science
Johnny, id101, M, Sports
Johnny, id101, M, Gym
Johnny, id101, M, English

Answer 1

You could use destructuring and spread operations and then map to recombine.

 data = [ ['Jenny', 'id100', 'F', 'English', 'Science', 'Math', 'Physics'], ['Johnny', 'id101', 'M', 'Science', 'Sports', 'Gym', 'English'] ]; result = []; data.map(row => { var [name, id, gender, ...prefs] = row; prefs.map((x) => result.push([name, id, gender, x])); }) console.log(result); 

As pointed out in the comments, since some of the features might not be available , here's a more conservative alternative.

 data.forEach(function(row) { prefs = row.slice(3); prefs.map(function(x) { result.push([row[0], row[1], row[2], x]) }); }) 

Answer 2

Try this:

function addingRows() {
  var ss=SpreadsheetApp.getActive();
  var sh=ss.getSheetByName('Sheet1');
  var rg=sh.getRange(2, 1, sh.getLastRow()-1,sh.getLastColumn());
  var vA=rg.getValues();
  var vB=[];
  for(var i=0;i<vA.length;i++) {
    vt=vA[i].slice(3);
    for(var j=0;j<vt.length;j++) {
      vB.push([vA[i][0],vA[i][1],vA[i][2],vt[j]])
    }
  }
  var osh=ss.getSheetByName('Sheet2');
  osh.appendRow(['Name','ID','Gender','Course']);
  osh.getRange(2,1,vB.length,4).setValues(vB);
}

My Sheet1:

My Sheet2:

• Array.slice