I am new to Prolog and wanted to access specific elements of the list.For eg-
L=[name,age,height,weight,gender]
How can I access age and height from this list as I want to compare them with some given values???
A list is not intended to be used as a record. Anyway, just use unification
L = [Name,Age,Height,Weight,Gender],
( Gender == male -> ... ; ... )
Related
List<EPosition> has S and P role.
For some employee, P role exists but now S does not exists.
So Source will only provide P but not S row in list.
In Database, WE have both P as well as S.
We want to make all S row as NULL (do not delete). So how to compare two lists
List<EPosition> src; //Fetch from Soap
List<EPosition> db;//Fetch from DB
for (EPosition d: db){
for (Eposition s: src){
if (s.ID = d.ID){
//Make it null
}
}
}
merge later
Problem statement: From the problem statement, what I understood is you have two lists (say A and B), where A contains some objects which are also present in B and you want to set this value to null in A using java streams.
Solution: So to do that you need to use the map on stream where each object is mapped to null if you find the object in B else object itself. To find whether the object is present in B there are two ways :
a. use contains method of the list (this will use equals method of the object in your case Eposition)
dbs = dbs.stream()
.map(db -> return src.contains(db) ? null :db)
.collect(Collectors.toList());
b. simply iterate over second list using stream and find a match of the id using anyMatch function.
dbs = dbs.stream()
.map(db -> return src.stream().anyMatch(sid -> sid.ID.equals(did.ID) ? null :db)
.collect(Collectors.toList());
This should be a very simple requirement. But it seems impossible to implement in DAX.
Data model, User lookup table joined to many "Cards" linked to each user.
I have a measure setup to count rows in CardUser. That is working fine.
<measureA> = count rows in CardUser
I want to create a new measure,
<measureB> = IF(User.boolean = 1,<measureA>, 16)
If User.boolean = 1, I want to return a fixed value of 16. Effectively, bypassing measureA.
I can't simply put User.boolean = 1 in the IF condition, throws an error.
I can modify measureA itself to return 0 if User.boolean = 1
measureA> =
CALCULATE (
COUNTROWS(CardUser),
FILTER ( User.boolean != 1 )
)
This works, but I still can't find a way to return 16 ONLY if User.boolean = 1.
That's easy in DAX, you just need to learn "X" functions (aka "Iterators"):
Measure B =
SUMX( VALUES(User.boolean),
IF(User.Boolean, [Measure A], 16))
VALUES function generates a list of distinct user.boolean values (1, 0 in this case). Then, SUMX iterates this list, and applies IF logic to each record.
New to cascading, trying to find out a way to get top N tuples based on a sort/order. for example, I'd like to know the top 100 first names people are using.
here's what I can do similar in teradata sql:
select top 100 first_name, num_records
from
(select first_name, count(1) as num_records
from table_1
group by first_name) a
order by num_records DESC
Here's similar in hadoop pig
a = load 'table_1' as (first_name:chararray, last_name:chararray);
b = foreach (group a by first_name) generate group as first_name, COUNT(a) as num_records;
c = order b by num_records DESC;
d = limit c 100;
It seems very easy to do in SQL or Pig, but having a hard time try to find a way to do it in cascading. Please advise!
Assuming you just need the Pipe set up on how to do this:
In Cascading 2.1.6,
Pipe firstNamePipe = new GroupBy("topFirstNames", InPipe,
new Fields("first_name"),
);
firstNamePipe = new Every(firstNamePipe, new Fields("first_name"),
new Count("num_records"), Fields.All);
firstNamePipe = new GroupBy(firstNamePipe,
new Fields("first_name"),
new Fields("num_records"),
true); //where true is descending order
firstNamePipe = new Every(firstNamePipe, new Fields("first_name", "num_records")
new First(Fields.Args, 100), Fields.All)
Where InPipe is formed with your incoming tap that holds the tuple data that you are referencing above. Namely, "first_name". "num_records" is created when new Count() is called.
If you have the "num_records" and "first_name" data in separate taps (tables or files) then you can set up two pipes that point to those two Tap sources and join them using CoGroup.
The definitions I used were are from Cascading 2.1.6:
GroupBy(String groupName, Pipe pipe, Fields groupFields, Fields sortFields, boolean reverseOrder)
Count(Fields fieldDeclaration)
First(Fields fieldDeclaration, int firstN)
Method 1
Use a GroupBy and group them base on the columns required and u can make use of secondary sorting that is provided by the cascading ,by default it provies them in ascending order ,if we want them in descing order we can do them by reverseorder()
To get the TOP n tuples or rows
Its quite simple just use a static variable count in FILTER and increment it by 1 for each tuple count value increases by 1 and check weather it is greater than N
return true when count value is greater than N or else return false
this will provide the ouput with first N tuples
method 2
cascading provides an inbuit function unique which returns firstNbuffer
see the below link
http://docs.cascading.org/cascading/2.2/javadoc/cascading/pipe/assembly/Unique.html
I have a list of type int, which contains ID's. For example it may contain 1,2,5,8,16 or 2,3,6,9,10,12 etc..
I then want to return all of my "Enquiries" based on the ID's stored in my list (called vehicles) and return them as a list, something like:
var enquiries = context.Enquiries.Where(x => x.EnquiryID == vehicles.Any()).ToList();
But obviously this doesn't work, is there something similar I can do?
You likely want to use Contains. Contains (in Linq2SQL or EF) will be transformed into a WHERE/IN clause.
enquiries = context.Enquiries
.Where( x => vehicles.Contains( x.EnquiryID ) )
.ToList();
So I have a list(table) of about 100k items and I want to retrieve all values that match a given list.
I have something like this.
the Table Sections key is NOT a primary key, so I'm expecting each value in listOfKeys to return a few rows.
List<int> listOfKeys = new List<int>(){1,3,44};
var allSections = Sections.Where(s => listOfKeys.Contains(s.id));
I don't know if it makes a difference but generally listOfKeys will only have between 1 to 3 items.
I'm using the Entity Framework.
So my question is, is this the best / fastest way to include a list in a linq expression?
I'm assuming that it isn't better to use another .NETICollection data object. Should I be using a Union or something?
Thanks
Suppose the listOfKeys will contain only small about of items and it's local list (not from database), like <50, then it's OK. The query generated will be basically WHERE id in (...) or WHERE id = ... OR id = ... ... and that's OK for database engine to handle it.
A Join would probably be more efficient:
var allSections =
from s in Sections
join k in listOfKeys on s.id equals k
select s;
Or, if you prefer the extension method syntax:
var allSections = Sections.Join(listOfKeys, s => s.id, k => k, (s, k) => s);