CouchDB Group By Values, Date Range - view

I have a bunch of documents in a CouchDB instance with the following data:
{
"_id": "[string based ID generated by CouchDB]",
"action": "view",
"group": [Integer representing a group number],
"date": [Javascript timestamp]
}
I can use the following to group data by group and action and to get the total number of actions per group:
function(doc) {
emit([doc.group, doc.action], [1, 1]);
}
(With reduce simply being _sum).
The issue is, this fetches data from all groups, whereas I only want the data from a single group (e.g. from group 1).
Also, I know I can do something like this to filter by date, but how would I combine it with the above to filter by date and by group ID?
function(doc) {
var then = new Date(Date.parse(doc['Event Date']));
var fatalities = 0;
if (doc['Total Fatal Injuries']!="") {
fatalities = parseInt(doc['Total Fatal Injuries']);
}
emit([then.getFullYear(), then.getMonth()], [1, fatalities]);
}
(From https://cloudant.com/blog/mapreduce-from-the-basics-to-the-actually-useful/)
Thanks!

I think you have your map() and reduce() functions correct already, you simply need to pass reduce=true&group_level=1&startkey=[<group id>]&endkey=[<group id>.toString() + "a"] to the view.
As for the filtering by date, you can use the same strategy. Using the group level, you can see sums per year and per month.

Related

How to get dynamic field count in dc.js numberDisplay?

I'm currently trying to figure out how to get a count of unique records to display using DJ.js and D3.js
The data set looks like this:
id,name,artists,genre,danceability,energy,key,loudness,mode,speechiness,acousticness,instrumentalness,liveness,valence,tempo,duration_ms,time_signature
6DCZcSspjsKoFjzjrWoCd,God's Plan,Drake,Hip-Hop/Rap,0.754,0.449,7,-9.211,1,0.109,0.0332,8.29E-05,0.552,0.357,77.169,198973,4
3ee8Jmje8o58CHK66QrVC,SAD!,XXXTENTACION,Hip-Hop/Rap,0.74,0.613,8,-4.88,1,0.145,0.258,0.00372,0.123,0.473,75.023,166606,4
There are 100 records in the data set, and I would expect the count to display 70 for the count of unique artists.
var ndx = crossfilter(spotifyData);
totalArtists(ndx);
....
function totalArtists(ndx) {
// Select the artists
var totalArtistsND = dc.numberDisplay("#unique-artists");
// Count them
var dim = ndx.dimension(dc.pluck("artists"));
var uniqueArtist = dim.groupAll();
totalArtistsND.group(uniqueArtist).valueAccessor(x => x);
totalArtistsND.render();
}
I am only getting 100 as a result when I should be getting 70.
Thanks a million, any help would be appreciated
You are on the right track - a groupAll object is usually the right kind of object to use with dc.numberDisplay.
However, dimension.groupAll doesn't use the dimension's key function. Like any groupAll, it looks at all the records and returns one value; the only difference between dimension.groupAll() and crossfilter.groupAll() is that the former does not observe the dimension's filters while the latter observes all filters.
If you were going to use dimension.groupAll, you'd have to write reduce functions that watch the rows as they are added and removed, and keeps a count of how many unique artists it has seen. Sounds kind of tedious and possibly buggy.
Instead, we can write a "fake groupAll", an object whose .value() method returns a value dynamically computed according to the current filters.
The ordinary group object already has a unique count: the number of bins. So we can create a fake groupAll which wraps an ordinary group and returns the length of the array returned by group.all():
function unique_count_groupall(group) {
return {
value: function() {
return group.all().filter(kv => kv.value).length;
}
};
}
Note that we also have to filter out any bins of value zero before counting.
Use the fake groupAll like this:
var uniqueArtist = unique_count_groupall(dim.group());
Demo fiddle.
I just added this to the FAQ.

Plotting aggregated data with sub-columns in dc.js

I have data in the form:
data = [..., {id:X,..., turnover:[[2015,2017,2018],[2000000,3000000,2800000]]}, ...];
My goal is to plot the year in the x-axis, against the average turnover for all companies currently selected via crossfilter in the y-axis.
The years recorded per company are inconsistent, but there should always be three years.
If it would help, I can reorganise the data to be in the form:
data = [..., {id:X,..., turnover:{2015:2000000, 2017:3000000, 2018:2800000}}, ...];
Had I been able to reorganise the data further to look like:
[...{id:X, ..., year:2015, turnover:2000000},{id:X,...,year:2017,turnover:3000000},{id:X,...,year:2018,turnover:2800000}];
Then this question would provide a solution.
But splitting the companies into separate rows doesn't make sense with everything else I'm doing.
Unless I'm mistaken, you have what I call a "tag dimension", aka a dimension with array keys.
You want each row to be recorded once for each year it contains, but you only want it to affect this dimension. You don't want to observe the row multiple times in the other dimensions, which is why you don't want to flatten.
With your original data format, your dimension definition would look something like:
var yearsDimension = cf.dimension(d => d.turnover[0], true);
The key function for a tag dimension should return an array, here of years.
This feature is still fairly new, as crossfilter goes, and a couple of minor bugs were found this year. These bugs should be easy to avoid. The feature has gotten a lot of use and no major bugs have been found.
Always beware with tag dimensions, since any aggregations will add up to more than 100% - in your case 300%. But if you are doing averages across companies for a year, this should not be a problem.
pairs of tags and values
What's unique about your problem is that you not only have multiple keys per row, you also have multiple values associated with those keys.
Although the crossfilter tag dimension feature is handy, it gives you no way to know which tag you are looking at when you reduce. Further, the most powerful and general group reduction method, group.reduce(), doesn't tell you which key you are reducing..
But there is one even more powerful way to reduce across the entire crossfilter at once: dimension.groupAll()
A groupAll object behaves like a group, except that it is fed all of the rows, and it returns only one bin. If you use dimension.groupAll() you get a groupAll object that observes all filters except those on that dimension. You can also use crossfilter.groupAll if you want a groupAll that observes all filters.
Here is a solution (using ES6 syntax for brevity) of reduction functions for groupAll.reduce() that reduces all of the rows into an object of year => {count, total}.
function avg_paired_tag_reduction(idTag, valTag) {
return {
add(p, v) {
v[idTag].forEach((id, i) => {
p[id] = p[id] || {count: 0, total: 0};
++p[id].count;
p[id].total += v[valTag][i];
});
return p;
},
remove(p, v) {
v[idTag].forEach((id, i) => {
console.assert(p[id]);
--p[id].count;
p[id].total -= v[valTag][i];
})
return p;
},
init() {
return {};
}
};
}
It will be fed every row and it will loop over the keys and values in the row, producing a count and total for every key. It assumes that the length of the key array and the value array are the same.
Then we can use a "fake group" to turn the object on demand into the array of {key,value} pairs that dc.js charts expect:
function groupall_map_to_group(groupAll) {
return {
all() {
return Object.entries(groupAll.value())
.map(([key, value]) => ({key,value}));
}
};
}
Use these functions like this:
const red = avg_paired_tag_reduction('id', 'val');
const avgPairedTagGroup = turnoverYearsDim.groupAll().reduce(
red.add, red.remove, red.init
);
console.log(groupall_map_to_group(avgPairedTagGroup).all());
Although it's possible to compute a running average, it's more efficient to instead calculate a count and total, as above, and then tell the chart how to compute the average in the value accessor:
chart.dimension(turnoverYearsDim)
.group(groupall_map_to_group(avgPairedTagGroup))
.valueAccessor(kv => kv.value.total / kv.value.count)
Demo fiddle.

Spring data mongo - Get sum of array of object

I have the following document:
{
pmv: {
budgets: [
{
amount: 10
},
{
amount: 20
}
]
}
}
and I need to sum the amount field from every object in budgets. But it's also possible that the budget object doesn't exist so I need to check that.
How could I do this? I've seen many questions but with projections, I just need a integer number which in this case would be 30.
How can I do it?
Thanks.
EDIT 1 FOR PUNIT
This is the code I tried but its giving me and empty aray
AggregationOperation filter = match(Criteria.where("pmv.budgets").exists(true).not().size(0));
AggregationOperation unwind = unwind("pmv.budgets");
AggregationOperation sum = group().sum("budgets").as("amount");
Aggregation aggregation = newAggregation(filter, unwind, sum);
mongoTemplate.aggregate(aggregation,"Iniciativas",String.class);
AggregationResults<String> aggregationa = mongoTemplate.aggregate(aggregation,"Iniciativas",String.class);
List<String> results = aggregationa.getMappedResults();
You can do this with aggregation pipeline
db.COLLECTION_NAME.aggregate([
{"pmv.budgets":{$exists:true,$not:{$size:0}}},
{$unwind:"$pmv.budgets"},
{amount:{$sum:"$pmv.budgets"}}
]);
This pipeline contains three queries:
get document having non-null and non-empty budgets
$unwind basically open the array and create one document for each array element. e.g. if one document of budgets has 3 elements then it will create 3 document and fill budgets property from each of the array element. You can read more about it here
sum all the budgets property using $sum operator
You can read more about aggregation pipeline here
EDIT: as per comments, adding code for java as well.
AggregationOperation filter = match(Criteria.where("pmv.budgets").exists(true).not().size(0));
AggregationOperation unwind = unwind("pmv.budgets");
AggregationOperation sum = group().sum("pmv.budgets").as("amount");
Aggregation aggregation = newAggregation(filter, unwind, sum);
mongoTemplate.aggregate(aggregation,COLLECTION_NAME,Output.class);
You can do this in more inline way as well but I wrote it like this so that it will be easy to understand.
I hope this answer your question.

Laravel Eloquent: Count Rows and group them by the day

I have a Model called "AdInteraction", these interactions can either be a click or a view (They either have boolean clicked or boolean viewed set to true).
Along every Interaction I save the created_at date.
Now this is what I want to end up with in order to have all the data I need to populate a ChartJS Chart:
[
{
"date": "01-01-2018"
"clicks": 13,
"views": 25
},
{
"date": "02-01-2018"
"clicks": 25,
"views": 74
},
{
"date": "03-01-2018"
"clicks": 0,
"views": 0
},
]
This is a query I already got on my Ad model which is related to AdInteraction:
public function getClicksForLastDays()
{
return $this->clicks()->get()->groupBy(function($date) {
return Carbon::parse($date->created_at)->format('y-m-d');
});
}
However this returns me an array of arrays looking like this:
What would be the correct and most efficient way to fetch the clicks and count them by days?
try this and let me know, I assume your column names are date,clicks,views, if its different then pls let me know, so I will adjust the answer or you can do it your self..
AdInteraction::select([DB::raw('DATE(date)'),DB::raw('count(case when clicks ="true" then 1 end) as "Clicks"'),
DB::raw('count(case when views ="true" then 1 end) as "Views"')])
->groupBy(DB::raw('DATE(date)'))
->get();
or try this
AdInteraction::select([DB::raw('DATE(date)'),DB::raw('count(case when clicks =true then 1 end) as "Clicks"'),
DB::raw('count(case when views =true then 1 end) as "Views"')])
->groupBy(DB::raw('DATE(date)'))
->get();
You should consider abandoning the idea of grouping by date using datetime column since such query will be very inefficient. When you, for example, GROUP BY DATE(created_at) MySQL will be performing this cast function for each row and won't be able to utilize indexes for created_at.
Therefore I recommend you to denormalize your table by introducing separate DATE created_date_at column for created_at value and create an index for it. Then you will be able to efficiently group your stats by this new column value. Just be sure to register the following code for your model:
AdInteraction::creating(function ($adInteraction) {
$adInteraction->created_date_at = $adInteraction->created_at->format('Y-m-d');
});
Or you can consider creating separate int columns for year, month and day. Then you can create a multi-column index and group by these columns. This way you will be able to also easily retrieve stats by days, months and years if needed.

Year over Year Stats from a Crossfilter Dataset

Summary
I want to pull out Year over Year stats in a Crossfilter-DC driven dashboard
Year over Year (YoY) Definition
2017 YoY is the total units in 2017 divided by the total units in 2016.
Details
I'm using DC.js (and therefore D3.js & Crossfilter) to create an interactive Dashboard that can also be used to change the data it's rendering.
I have data, that though wider (has ~6 other attributes in addition to date and quantity: size, color, etc...sales data), boils down to objects like:
[
{ date: 2017-12-7, quantity: 56, color: blue ...},
{ date: 2017-2-17, quantity: 104, color: red ...},
{ date: 2016-12-7, quantity: 60, color: red ...},
{ date: 2016-4-15, quantity: 6, color: blue ...},
{ date: 2017-2-17, quantity: 10, color: green ...},
{ date: 2016-12-7, quantity: 12, color: green ...}
...
]
I'm displaying one rowchart per attribuet such that you can see the totals by color, size, etc. People would use each of these charts to be able to see the totals by that attribute and drill into the data by filtering by just a color, or a color and a size, or a size, etc. This setup is all (relatively) straight forward and kind of what DC is made for.
However, now I'd like to add some YoY stats such that I can show a barchart with x-axis as the years, and the y-axis as the YoY values (ex. YoY-2019 = Units-2019 / Units-2018). I'd also like to do the same by quarter and month such that I could see YoY Mar-2019 = Units-Mar-2019 / Units-Mar-2018 (and the same for quarter).
I have a year dimension and sum quantity
var yearDim = crossfilterObject.dimension(_ => _.date.getFullYear());
var quantityGroup = yearDim.group.reduceSum(_ => _.quantity);
I can't figure out how to do the Year over Year calc though in the nice, beautiful DC.js-way.
Attempted Solutions
Year+1
Add another dimension that's year + 1. I didn't' really get any further though because all I get out of it are two dimensions whose year groups I want to divide ... but am not sure how.
var yearPlusOneDim = crossfilterObject.dimension(_ => _.date.getFullYear() + 1);
Visually I can graph the two separately and I know, conceptually, what I want to do: which is divide the 2017 number in yearDim by the 2017 number in YearPlusOneDim (which, in reality, is the 2016 number). But "as a concept is as far as I got on this one.
Abandon DC Graphing
I could always use the yearDim's quantity group to get the array of values, which I could then feed into a normal D3.js graph.
var annualValues = quantityGroup.all();
console.log(annualValues);
// output = [{key: 2016, value: 78}, {key: 2017, value: 170}]
// example data from the limited rows listed above
But this feels like a hacky solution that's bound to fail and not benefit from all the rapid and dynamic DC updating.
I'd use a fake group, in order to solve this in one pass.
As #Ethan says, you could also use a value accessor, but then you'd have to look up the previous year each time a value is accessed - so you'd probably have to keep an extra table around. With a fake group, you only need this table in the body of your .all() function.
Here's a quick sketch of what the fake group might look like:
function yoy_group(group) {
return {
all: function() {
// index all values by date
var bydate = group.all().reduce(function(p, kv) {
p[kv.key.getTime()] = kv.value;
return p;
}, {});
// for any key/value pair which had a value one year earlier,
// produce a new pair with the ratio between this year and last
return group.all().reduce(function(p, kv) {
var date = d3.timeYear.offset(kv.key, -1);
if(bydate[date.getTime()])
p.push({key: kv.key, value: kv.value / bydate[date.getTime()]});
return p;
}, []);
}
};
}
The idea is simple: first index all the values by date. Then when producing the array of key/value pairs, look each one up to see if it had a value one year earlier. If so, push a pair to the result (otherwise drop it).
This should work for any date-keyed group where the dates have been rounded.
Note the use of Array.reduce in a couple of places. This is the spiritual ancestor of crossfilter's group.reduce - it takes a function which has the same signature as the reduce-add function, and an initial value (not a function) and produces a single value. Instead of reacting to changes like the crossfilter one does, it just loops over the array once. It's useful when you want to produce an object from an array, or produce an array of different size from the original.
Also, when indexing an object by a date, I use Date.getTime() to fetch the numeric representation of the date. Otherwise the date coerces to a string representation which may not be exact. Probably for this application it would be okay to skip .getTime() but I'm in the habit of always comparing dates exactly.
Demo fiddle of YOY trade volume in the data set used by the stock example on the main dc.js page.
I've rewritten #Gordon 's code below. All the credit is his for the solution (answered above) and I've just wirtten down my own version (far longer and likely only useful for beginners like me) of the code (much more verbose!) and the explanation (also much more verbose) to replicate my thinking in bridging my near-nothing starting point up to #Gordon 's really clever answer.
yoyGroup = function(group) {
return { all: function() {
// For every key-value pair in the group, iterate across it, indexing it by it's time-value
var valuesByDate = group.all().reduce(function(outputArray, thisKeyValuePair) {
outputArray[thisKeyValuePair.key.getTime()] = thisKeyValuePair.value;
return outputArray;
}, []);
return group.all().reduce(function(newAllArray, thisKeyValuePair) {
var dateLastYear = d3.timeYear.offset(thisKeyValuePair.key, -1);
if (valuesByDate[dateLastYear.getTime()]) {
newAllArray.push({
key: thisKeyValuePair.key,
value: thisKeyValuePair.value / valuesByDate[dateLastYear.getTime()] - 1
});
}
return newAllArray;
}, []); // closing reduce() and a function(...)
}}; // closing the return object & a function
};
¿Why are we overwritting the all() function?
When DC.js goes to create a graph based on a grouping, the only function from Crossfilter it uses is the all() function. So if we want to do something custom to a grouping to affect a DC graph, we only have to overwrite that one function: all().
¿What does the all() function need to return?
A group's all function must return an array of objects and each object must have two properties: key & value.
¿So what exactly are we doing here?
We're starting with an existing group which shows some values over time (Important Assumption: keys are date objects) and then creating a wrapper around it so that we can take advantage of the work that crossfilter has already done to aggregate at a certain level (ex. year, month, etc.).
We start by using reduce to manipulate the array of objects into a more simple array where the keys and values that were in the objects are now directly in the array. We do this to make it easier to look up values by keys.
before / output structure of group.all()
[ {key: k1, value: v1},
{key: k2, value: v2},
{key: k3, value: v3}
]
after
[ k1: v1,
k2: v2,
k3: v3
]
Then we move on to creating the correct all() structure again: an array of objects each of which has a key & value property. We start with the existing group's all() array (once again), but this time we have the advantage of our valuesByDate array which will make it easy to look up other dates.
So we iterate (via reduce) over the original group.all() output and lookup in the array we generated earlier (valuesByDate), if there's an entry from one year ago (valuesByDate[dateLastYear.getTime()]). (We use getTime() so it's simple integers rather than objects we're indexing off of.) If there is an element of the array from one year ago, then we add a key-value object-pair to our soon-to-be-returned array with the current key (date) and for the value we divide the "now" value (thisKeyValuePair.value) by the value 1 year ago: valuesByDate[dateLastYear.getTime()]. Lastly we subtract 1 so that it's (the most traditional definition of) YoY. Ex. This year = 110 and last year = 100 ... YoY = +10% = 110/100 - 1.

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