MongoDB: Query float range on array

Question

i am facing a strange behaviuor with mongo-shell und Spring Data Mongodb

Here is my example query:

> db.substances.find({"precursor.mass": {$gte:159.9900,$lte:160.0100}}).count()
6

So i want to find mass values in a given range (plus/minus). In this example the input was 160 +/- 0.01.

Here are two out of the six results. The frist one is ok, but I can not explain and understand why the second result is found.

{
"_id" : ObjectId("524bfe80729458abfd7698a5"),
"exactMass" : 159.1259,
"nominalMass" : 159,
"molarMass" : 159.22,
"status" : 1,
"decompositions" : [ ],
"precursor" : [
    {
        "mass" : 160,
        "ion" : "+H",
        "charge" : "+",
        "fragments" : [
            55,
            83,
            124,
            97,
            69,
            142
        ]
    }
],
}

{
"_id" : ObjectId("524bfe80729458abfd7695be"),
"exactMass" : 159.068414,
"nominalMass" : 159,
"molarMass" : 159.19,
"status" : 0,
"decompositions" : [ ],
"precursor" : [
    {
        "mass" : 158.0611,
        "ion" : "-H",
        "charge" : "-",
        "fragments" : [ ]
    },
    {
        "mass" : 160.0756,
        "ion" : "+H",
        "charge" : "+",
        "fragments" : [ ]
    }
],
}

What am I overlooking? I Suppose i am using a wrong query?

My goal is to find all substances where ANY of the precursor.mass is between a given value +/- a tolerance.

kamituel · Accepted Answer · 2013-10-15 12:20:52Z

3

From the mongo doc on find():

If a field contains an array and your query has multiple conditional operators, the field as a whole will match if either a single array element meets the conditions or a combination of array elements meet the conditions.

So, since {"mass" : 158.0611} matches second query criterion (is less than 160.0100), and {"mass" : 160.0756} matches first (is greater than 159.9900), the whole array matches.

What you're looking for is $elemMatch:

db.substances.find({
  "precursor": { 
    $elemMatch: {
      mass: { $gt:159.9900, $lt:160.0100 }
    }
  }
}).pretty()

edited Oct 15, 2013 at 12:20

answered Oct 15, 2013 at 11:43

kamituel

36.2k6 gold badges86 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

MongoDB: Query float range on array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related