Node formatting

[valoricDe]

Is there an elegant solution to format Nodes? Currently in lib/utils/string.js:90-100 (after if (value && typeof value === 'object') {) it's calling toString. But calling format would be nicer :D So every number in the Node is formatted.

My naive solution would be to iterate through all properties of a node into depth and substitute ConstantNodes by their formatted pendant. Or to check for every Node type and act accordingly. But I guess this logic is already somewhere present?

Example of wished for behaviour: math.format("x = 10.123456789", {decimals: 5}) returns "x = 10.12345"

[josdejong]

That's an interesting idea. There is currently elegant no solution for this.

You can use the handler option of toString which works but is a bit cumbersome:

function toStringHandler(node, options) {
  if (node.isConstantNode) {
    if (node.valueType === 'string') {
      return '"' + node.value + '"';
    }
    else {
      return math.format(math.eval(node.value), { precision: 5})
    }
  }
  else {
    return undefined;
  }
}

var expr = 'x = 10.123456789';
var str = math.parse(expr).toString({ handler: toStringHandler });
console.log(str); // x = 10.123

Maybe we should introduce a new option to pass a format function, that could work like this:

var expr = 'x = 10.123456789';
var str = math.parse(expr).toString({ 
  format: function (value) {
    return math.format(value, { precision: 5}); 
  }
 });
console.log(str); // x = 10.123

and we could extend the existing function math.format to accept a node tree:

var expr = 'x = 10.123456789';
var str = math.format(math.parse(expr), { precision: 5});
console.log(str); // x = 10.123

[valoricDe]

Thank you very much. The first option works like a charm. But I agree that including it into math.format would be perfect. Unfortunately I do not have the time to do it right now.

[josdejong]

👍 let's keep this issue open as a feature request for this format option.