将集合中的所有MongoDB浮点值四舍五入到小数点后两位

Question

Is there a quick and easy way to tell Mongo that for properties that have values that are floats with over 10 decimal places that I do not care about that level of detail and would like all values to be rounded to 2 decimal places?

eg, in collection X I have

{'a': 13.4823423, 'b': 12.423424524342342}

and many similar documents thousands of times over, and I want

{'a': 13.48, 'b': 12.42}

I know this is a failure on my end of inputting the data this way, and in my head the quick fix would be a python script to go over everything and round it, but my question is specifically is there a built in Mongo command that handles cases like this really well? . Thanks.

Answer 1

You can use Math.round with Math.pow. For example, you can get 13.48 as

Math.round(x['a'] * Math.pow(10,2)) * Math.pow(10, -2)

Not fancy, but workable.