counting child nodes using XPATH - xpath

I have following XML
<orderList>
<orderInfo orderId="xyz" returnCode="Pending" />
<orderInfo orderId="yzz" returnCode="Shipped">
<orderDetail shipped-date="xxxx-xx-xx xx:xx:xx">
<order>
....
</order>
</orderDetail>
</orderInfo>
</orderList>
I want to count # of order under each orderDetail item ...
I tried this link (XPath to count the child nodes based on complex filter) but it didn't help
I came up with this path
count(//orderList/orderInfo/orderDetail[count(order)])

If you want to count all order elements in the orderList/orderInfo/orderDetail nodes (ignoring their current context), then you could use:
count(//orderList/orderInfo/orderDetail/order)
If you want to count the number of orders for a specific orderDetail, then you should use a predicate to select which orderDetail you want:
count(//orderList/orderInfo/orderDetail[#shipped-date="xxxx-xx-xx xx:xx:xx"]/order)
Unless you are using XPath 2.0 or a greater version, you won't be able to return a collection of results with a single expression. But you can select all orderDetail elements (//orderList/orderInfo/orderDetail), iterate through them and count the order elements in the current context, or set the predicate value as a variable to select a specific orderDetail.

Related

List.Distinct and List.Count Challenge

Within PQ, I have a table of data (below) to which I am trying to determine whether all the columns titled Plan Status-# are the same, excluding blanks, and if all the same, display that value and if not display "Varies across plans"
The PQ code is below where I use List.Distinct to create a list of all "unique values".
I then use List.Count to count this number in the list and if 1, set the column equal to the Distinct value.
If List.Count({List.Distinct({[#"Plan Status-H"],[#"Plan Status-D"],[#"Plan Status-S"],[#"Plan Status-M"],[#"Plan Status-C"],[#"Plan Status-U"]})})=1 then List.Distinct({[#"Plan Status-H"],[#"Plan Status-D"],[#"Plan Status-S"],[#"Plan Status-M"],[#"Plan Status-C"],[#"Plan Status-U"]}) else "Varies across plans"
As per the table above, the List.Count does not seem to working correctly as some of the records show a merged value of items in the list which means the List.Count for a list with multiple values is calcing as 1.
You have extra brackets in your code. Try this:
if List.Count(List.Distinct({[#"Plan Status-H"],[#"Plan Status-D"],[#"Plan Status-S"],[#"Plan Status-M"],[#"Plan Status-C"],[#"Plan Status-U"]}))=1
then List.Distinct({[#"Plan Status-H"],[#"Plan Status-D"],[#"Plan Status-S"],[#"Plan Status-M"],[#"Plan Status-C"],[#"Plan Status-U"]})
else "Varies across plans"

Get n-th result returned from MATCH query in Neo4J database

I've set up a library database where users borrow books. Using a MATCH Command i can return the book titles and number of their lendings by descending order.
My Cypher for returning the list of books and number of lendings is:
MATCH (user)-[:LENDING]->(b:Book)
RETURN b.title, COUNT(b.title) as numberOfRents
ORDER BY numberOfRents DESC
This is working properly. However, i need to get the n-th book(by lendings) returned only(let's say the third for example), which is something i failed to do until now.
Sounds like you need SKIP and LIMIT
MATCH (user)-[:LENDING]->(b:Book)
RETURN b.title, COUNT(b.title) as numberOfRents
ORDER BY numberOfRents DESC
SKIP 2 LIMIT 1
// skips the first 2, so you only get the 3rd

Order by random in RethinkDB

I want to order documents randomly in RethinkDB. The reason for this is that I return n groups of documents and each group must appear in order in the results (so all documents belonging to a group should be placed together); and I need to randomly pick a document, belonging to the first group in the results (you don't know which is the first group in the results - the first ones could be empty, so no documents are retrieved for them).
The solution I found to this is to randomly order each of the groups before concat-ing to the result, then always pick the first document from the results (as it will be random). But I'm having a hard time ordering these groups randomly. Would appreciate any hint or even a better solution if there is one.
If you want to order a selection of documents randomly you can just use .orderBy and return a random number using r.random.
r.db('test').table('table')
.orderBy(function (row) { return r.random(); })
If these document are in a group and you want to randomize them inside the group, you can just call orderBy after the group statement.
r.db('test').table('table')
.groupBy('property')
.orderBy(function (row) { return r.random(); })
If you want to randomize the order of the groups, you can just call orderBy after calling .ungroup
r.db('test').table('table')
.groupBy('property')
.ungroup()
.orderBy(function (row) { return r.random(); })
The accepted answer here should not be possible, as John mentioned the sorting function must be deterministic, which r.random() is not.
The r.sample() function could be used to return a random order of the elements:
If the sequence has less than the requested number of elements (i.e., calling sample(10) on a sequence with only five elements), sample will return the entire sequence in a random order.
So, count the number of elements you have, and set that number as the sample number, and you'll get a randomized response.
Example:
var res = r.db("population").table("europeans")
.filter(function(row) {
return row('age').gt(18)
});
var num = res.count();
res.sample(num)
I'm not getting this to work. I tried to sort an table randomly and I'm getting the following error:
e: Sorting by a non-deterministic function is not supported in:
r.db("db").table("table").orderBy(function(var_33) { return r.random(); })
Also I have read in the rethink documentation that this is not supported. This is from the rethinkdb orderBy documentation:
Sorting functions passed to orderBy must be deterministic. You cannot, for instance, order rows using the random command. Using a non-deterministic function with orderBy will raise a ReqlQueryLogicError.
Any suggestions on how to get this to work?
One simple solution would be to give each document a random number:
r.db('db').table('table')
.merge(doc => ({
random: r.random(1, 10)
})
.orderBy('random')

Slow Neo4j query despite indices

Here I'm trying to find all Twitter users who are followed by and who follow any members of some group G:
MATCH (x:User)-[:FOLLOWS]->(t:User)-[:FOLLOWS]->(y:User)
WHERE (x.screen_name IN {{G_SCREEN_NAMES}} OR x.id IN {{G_IDS}})
AND (y.screen_name IN {{G_SCREEN_NAMES}} OR y.id IN {{G_IDS}})
RETURN t.id
But for the group G I sometime have their screen names and sometimes have their ids, thus the OR clause above. Unfortunately this query is long running and doesn't appear to ever return.
I have indices and constraints on both on both id and screen_name:
Indexes
ON :User(screen_name) ONLINE (for uniqueness constraint)
ON :User(id) ONLINE (for uniqueness constraint)
Constraints
ON (user:User) ASSERT user.screen_name IS UNIQUE
ON (user:User) ASSERT user.id IS UNIQUE
If I get rid of the OR clause (for instance if I happen to have all screen_names or all ids for group G) then the query runs quite fast.
I'm using neo4j-community-2.1.3 on a Mac. My graph has 286039 nodes, all of which have the User label.
And ideas to improve this? Otherwise I'll have to chop this up into 4 queries to get all possible combinations of members. This is really even more problematic because I really want to keep track of how commonly a user appears in a G-->user-->G relationship, and I'll need to do a lot of extra bookkeeping if the counts are spread among 4 different queries.
Update
I created an issue related to this: https://github.com/neo4j/neo4j/issues/2834
I ended up using
MATCH (x:User) WHERE x.screen_name IN ["apple","banana","coconut"]
WITH collect(id(x)) as x_ids
MATCH (x:User) WHERE x.id in [12345,98765]
WITH x_ids+collect(id(x)) as x_ids
MATCH (y:User) WHERE y.screen_name IN ["apple","banana","coconut"]
WITH x_ids,collect(id(y)) as y_ids
MATCH (y:User) WHERE y.id in [12345,98765]
WITH x_ids,y_ids+collect(id(y)) as y_ids
MATCH (x:User)-[:FOLLOWS]->(t:User)-[:FOLLOWS]->(y:User)
WHERE id(x) in x_ids AND id(y) in y_ids
RETURN count(*) as c, t.screen_name,t.id
ORDER BY c DESC
LIMIT 1000
But this basically represents a hack to get around a place where neo4j isn't using the indices that it could be.
I guess the query does not make use of indexes due to the OR condition, you can verify by prefixing the query with PROFILE and run it in neo4j-shell.
If there's no notion of index usage, you might split the query up into two parts. The first one fetches the combined list of user ids, instead of the OR we do a UNION on two queries (each using a index lookup):
MATCH (x:User) WHERE x.screen_name in {G_SCREEN_NAMES} RETURN id(x) as ids UNION
MATCH (x:User) WHERE x.id in {G_IDS} RETURN id(x) as ids
On the client side, use the list of node ids as parameter for the next query:
MATCH (x:User)-[:FOLLOWS]->(t)-[:FOLLOWS]->(y)
WHERE id(x) in {ids} AND id(y) in {ids}
RETURN t.id
I've intentionally removed the labels for t and y with the assumption that you can only follow User and no other kind of nodes. This removes a unnecessary label check.
JnBrymn,
How about this query?
MATCH (x:User)
WHERE x.screen_name IN {{G_SCREEN_NAMES}} OR x.id IN {{G_IDS}}
WITH x
MATCH (x)-[:FOLLOWS]->(t:User)
WITH t
MATCH (t)-[:FOLLOWS]->(y:User)
WHERE y.screen_name IN {{G_SCREEN_NAMES}} OR y.id IN {{G_IDS}}
RETURN t.id
Grace and peace,
Jim

SOQL - single row per each group

I have the following SOQL query to display List of ABCs in my Page block table.
Public List<ABC__c> getABC(){
List<ABC__c> ListABC = [Select WB1__c, WB2__c, WB3__c, Number, tentative__c, Actual__c, PrepTime__c, Forecast__c from ABC__c ORDER BY WB3__c];
return ListABC;
}
As you can see in the above image, WB3 has number of records for A, B and C. But I want to display only 1 record for each WB3 group based on Actual__c. Only latest Actual__c must be displayed for each WB3 Group.
i.e., Ideally I want to display only 3 rows(one each for A,B,C) in this example.
For this, I have used GROUPBY and displayed the result using AggregateResults. Here is the result.
I got the Latest Actual Date for each WB3 as shown above. But the Tentative date is not corresponding to it. The Tentative Date is also the MAX in the list.
Here is the code I used
public List<SiteMonitoringOverview> getSPM(){
AggregateResult[] AgR = [Select WB_3__c, MAX(Tentaive_Date__c) dtTentativeDate , MAX(Actual_Date__c) LatestCDate FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
if(AgR.size()>0){
for(AggregateResult SalesList : AgR){
CustSumList.add(new SiteMonitoringOverview(String.ValueOf(SalesList.ge​t('WB_3__c')), String.valueOf(SalesList.get('dtTentativeDate')), String.valueOF(SalesList.get('LatestCDate')) ));
}
}
return CustSumList;
}
I am forced to use MAX() for tentative date. I want the corresponding Tentative date of the MAX Actual Date. Not the Max Tentative Date.
For group A, the Tentative Date of Max Actual Date is 12/09/2012. But it is displaying the MAX tentative date: 27/02/2013. It should display 12/09/2012. This is because I am using MAX(Tentative_Date__c) in my code. Every column in the SOQL query must be either GROUPED or AGGREGATED. That's weird.
How do I get the required 3 rows in this example?
Any suggestions? Any different approach (looping within in groups)? how?
Just ran into this issue myself. The solution I came up with only works if you want the oldest or newest record from each grouping. Unfortunately it probably won't work in your case. I'll still leave this here incase it does happen to help someone searching for a solution to this issue.
AggregateResult[] groupedResults = [Select Max(Id), WBS_3__c FROM Site_progress_Monitoring__c GROUP BY WBS_3__c];
Calling MAX or MIN on the Id will let you get 1 record per group condition. You can then query other information. I my case I just need 1 record from each group and didn't really care which one it was.

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