Convert 1D Array to 2D Array and append Array to last Row of Sheet

Question

I am having 2 array lists from which i am finding the difference.

arr1 = ['Sam','Annie', 'Margorie', 'Ester', 'John'];
arr2 = ['Bill', 'Sally', 'Sam', 'Annie', 'Suman', 'Margorie', 'Ester', 'Pierre', 'John'];

var diff = arr2.filter(x => !arr1.includes(x));

console.log(diff) //result....diff = ['Bill', 'Sally', 'Suman', 'Pierre']

What i want to do is to modify the above Filter Arrow function to add 'New' for each item' so that the resultant array becomes:

//diff = [['Bill', 'New'] , ['Sally', 'New'] , ['Suman', 'New'] , ['Pierre' , 'New']]

I can do this separately using a Map Arrow function like this:

diff = diff.map(x => [x,'New']);

But i want to club both these functions together. Is that possible?
Also, when i try to append this array to the last row of the sheet, the last row shows 'Object@xxx' instead of the actual values.

e.g.

Sht.appendRow(diff);

What am i doing wrong?

TheMaster · Accepted Answer · 2020-07-26 20:32:41Z

2

To combine map/filter, Use a simple for-loop/if or reduce:

arr1 = ['Sam','Annie', 'Margorie', 'Ester', 'John'];
arr2 = ['Bill', 'Sally', 'Sam', 'Annie', 'Suman', 'Margorie', 'Ester', 'Pierre', 'John'];

const diff = arr2.reduce((diff,x) => !arr1.includes(x) ? [...diff , [x, "New"]] : diff, [] );

console.log(diff) //result....diff = ['Bill', 'Sally', 'Suman', 'Pierre']

Sheet#appendRow only accepts a 1D(1-dimensional) array. Use range.setValues() if you want to append a 2D array.

answered Jul 26, 2020 at 20:32

TheMaster

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4 Comments

sifar Over a year ago

Thanks. Just on a side note, can this be rewritten as normal javascript instead of using Arrow functions? I am still grappling with Arrow functions.

TheMaster Over a year ago

@sifar const diff = arr2.reduce(function(diff,x) { return !arr1.includes(x) ? [...diff , [x, "New"]] : diff}, [] ); or more elaborately const diff = arr2.reduce(function(diff,x) { if (!arr1.includes(x))return diff.concat([x, "New"]); return diff}, [] );

sifar Over a year ago

Excellent! But is there a reason for using Const instead of Var? And from a speed performance perspective, which should be faster for large ranges?

TheMaster Over a year ago

@sifar const or let is preferable due to scope restrictions and therefore less error-prone. var should generally be avoided. JavaScript tag info page has excellent resources.

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