I need to create some plots from single documents existing in mongodb. I can only use the mongodb aggregation framework (so for example I cannot just pull the documents into python and work with it there). I am using the query builder of metabase, so I am limited from this regard.
In order to do this, I am first using some $match queries in order to identify the documents that I need to look at (these are predefined and static). After the $match stage, I am left with one document (this is ok) with the following structure.
{
"id": 1,
"locs": {
"a":1,
"b":2,
"c":3
}
}
I need to change this structure to something like this:
[{"a":1}, {"b":2}, {"c":3"}]
or any other form that would allow me to create pie charts out of the structure.
Thanks!
You can convert locs object to array using $objectToArray. Now $unwind the locs array to split into multiple documents. Use $group with $push accumulator to make the split data again into k and v format. And finally use $replaceRoot with the final data field to move it to $$ROOT position.
db.collection.aggregate([
{ "$project": { "data": { "$objectToArray": "$locs" }}},
{ "$unwind": "$data" },
{ "$group": {
"_id": "$data",
"data": { "$push": { "k": "$data.k", "v": "$data.v" }}
}},
{ "$project": {
"data": { "$arrayToObject": "$data" }
}},
{ "$replaceRoot": { "newRoot": "$data" }}
])
Related
I have an aggregation query which calculates records by tag combinations this query is working well however it has one issue which is that it duplicates documents for tag combinations that are in different orders e.g. i could have one document with the tags: ['one', 'two'] and a second document with ['two' 'one'] the rest of the data would be exactly the same.
My first thought would be to do a $group aggregation query and search how to order the arrays in a project query however i cannot find anywhere how to do this. I did see for update queries you can use '$push' however this feature doesnt seem to exist for $project queries.
an example document at this phase is something like this
_id: "sadasdsad"
tags: ['one', 'two'],
total_count:37,
second_count:14,
what would be the best approach to solving this issue?
You can sort your array using $unwind,$sort and finally $group so all your tags are the same before grouping. Example : https://mongoplayground.net/p/EZi04LfY1ff
However, I would try to store those tags already sorted. So you can avoid these steps.
db.collection.aggregate({
"$unwind": "$tag"
},
{
"$sort": {
key: 1,
tag: 1
}
},
{
"$group": {
"_id": "$key",
"tag": {
"$push": "$tag"
}
}
},
{
"$group": {
"_id": "$tag",
"field": {
"$push": "$$ROOT"
}
}
})
I need a mongodb query to get the list or map of values with unique value of the field(f) as the key in the collection and count of documents having the same value in the field(f) as the mapped value. How can I achieve this ?
Example:
Document1: {"id":"1","name":"n1","city":"c1"}
Document2: {"id":"2","name":"n2","city":"c2"}
Document3: {"id":"3","name":"n1","city":"c3"}
Document4: {"id":"4","name":"n1","city":"c5"}
Document5: {"id":"5","name":"n2","city":"c2"}
Document6: {"id":"6,""name":"n1","city":"c8"}
Document7: {"id":"7","name":"n3","city":"c9"}
Document8: {"id":"8","name":"n2","city":"c6"}
Query result should be something like this if group by field is "name":
{"n1":"4",
"n2":"3",
"n3":"1"}
It would be nice if the list is also sorted in the descending order.
It's worth noting, using data points as field names (keys) is somewhat considered an anti-pattern and makes tooling difficult. Nonetheless if you insist on having data points as field names you can use this complicated aggregation to perform the query output you desire...
Aggregation
db.collection.aggregate([
{
$group: { _id: "$name", "count": { "$sum": 1} }
},
{
$sort: { "count": -1 }
},
{
$group: { _id: null, "values": { "$push": { "name": "$_id", "count": "$count" } } }
},
{
$project:
{
_id: 0,
results:
{
$arrayToObject:
{
$map:
{
input: "$values",
as: "pair",
in: ["$$pair.name", "$$pair.count"]
}
}
}
}
},
{
$replaceRoot: { newRoot: "$results" }
}
])
Aggregation Explanation
This is a 5 stage aggregation consisting of the following...
$group - get the count of the data as required by name.
$sort - sort the results with count descending.
$group - place results into an array for the next stage.
$project - use the $arrayToObject and $map to pivot the data such
that a data point can be a field name.
$replaceRoot - make results the top level fields.
Sample Results
{ "n1" : 4, "n2" : 3, "n3" : 1 }
For whatever reason, you show desired results having count as a string, but my results show the count as an integer. I assume that is not an issue, and may actually be preferred.
document:
{"_id":"5cb0dfe234a8a30c9c0af127",
"sensors":
[{"value0":0.153,
"value1":-0.306,
"value2":9.807}],
"timestamp":1555095522489,"__v":0}
I want to get 4 field (timestamp and value 0..2) without any array / object.
unwind work only against array but not objects. What should I do?
desired output :
{timestamp":1555095522489,
value0":0.153,
value1":-0.306,
value2":9.807}
Use $unwind and $replaceRoot aggregation operators
db.collection.aggregate([
{ "$unwind": "$sensors" },
{ "$replaceRoot": { "newRoot": { "$mergeObjects": ["$sensors", { "timestamp": "$timestamp" }] }}}
])
I have a mongodb query that results data in the following format
[{"_id":1471424941,"value":[1444,0]},{"_id":1471424941,"value":[1444,0]}]
and I would like to convert the result into
[[1471424941, 1444,0],[1471424941, 1444,0]]
Will this be possible using aggregate method ? I want to avoid using Javascript for the conversion and want to do it using mongodb if possible.
Can MongoDb produce an aggreation that will remote the value of the keys from the result
Run the following aggregation pipeline which uses the $concatArrays operator to concatenate arrays and get the desired result as a key:
db.collection.aggregate([
{
"$project": {
"items": { "$concatArrays": [ "$value", ["$_id"] ] }
}
},
{
"$group": {
"_id": null,
"items": { "$push": "$items" }
}
}
])
i want to find accepted bodypart which have status active
i tried this
db.patients.find({
"injury.injurydata.injuryinformation.dateofinjury": {
"$gte": ISODate("2014-05-21T08:00:00Z") ,
"$lt": ISODate("2014-06-03T08:00:00Z")
},
{
"injury.injurydata.acceptedbodyparts":1,
"injury.injurydata.injuryinformation.dateofinjury":1
"injury":{
$elemMatch: {
"injury.injurydata.acceptedbodyparts.status": "current"
}
}
})
but still get both array
If acceptedbodyparts is an array, you can't query acceptedbodyparts.status. If status is a field on the documents contained in the array, you would need to use another $elemMatch clause in your query. So the last part would look something like this:
{"injury":{ "$elemMatch": { "injurydata.acceptedbodyparts": {"$elemMatch": {"status":"current"} }} }}
I also removed the injury. prefix in the first $elemMatch because you're querying data within the injury array.
Note that this will return the entire document with the full array, as long as it contains the document you're searching for. If your intention is to retrieve a particular element in an array, $elemMatch is the wrong approach.
Standard projection will not work with nested arrays or limiting any fields inside arrays. For that you need the aggregation framework:
db.patients.aggregate([
// First match, Matches documents
{ "$match": {
"injury.injurydata.injuryinformation.dateofinjury": {
"$gte": ISODate("2014-05-21T08:00:00Z"),
"$lt": ISODate("2014-06-03T08:00:00Z")
}
}},
// Un-wind the arrays
{ "$unwind": "$injury" },
{ "$unwind": "$injury.injurydata" },
{ "$unwind": "$injury.injurydata.acceptedbodyparts" },
// Now match the required data in the array
{ "$match": {
"injury.injurydata.acceptedbodyparts.status": "current"
}},
// Group only wanted fields
{ "$group": {
"_id": "$_id",
"acceptedbodyparts": {
"$push": "injury.injurydata.acceptedbodyparts"
}
}}
])
You can add in other fields outside of the array either using $first or by akin g them part of the _id in the grouping.
This is just something that is outside of the scope of the standard projection available and the aggregation framework with the extended manipulation capabilities solves this.