I am a new NetLogo user. How do I get the property of sorted turtles?
clear-all
create-turtles 5
foreach (sort turtles) [ask ? [show who]]
However, the above code produces the error below
ERROR: Nothing named ? has been defined.
The syntax of foreach changed with NetLogo 6 and the question mark syntax is no longer supported. The proper syntax is shown at
https://ccl.northwestern.edu/netlogo/docs/dictionary.html#foreach
So, in your case the command would be
foreach (sort turtles) [n -> ask n [show who]]
where "n" is taking on the role of the old "?".
Check out the description of anonymous procedures in the NelLogo dictionary at
https://ccl.northwestern.edu/netlogo/docs/dictionary.html#arrow
Charles
Related
I can query using Cypher in Neo4j from the Panama database the countries of three types of identity holders (I define that term) namely Entities (companies), officers (shareholders) and Intermediaries (middle companies) as three attributes/columns. Each column has single or double entries separated by colon (eg: British Virgin Islands;Russia). We want to concatenate the countries in these columns into a unique set of countries and hence obtain the count of the number of countries as new attribute.
For this, I tried the following code from my understanding of Cypher:
MATCH (BEZ2:Officer)-[:SHAREHOLDER_OF]->(BEZ1:Entity),(BEZ3:Intermediary)-[:INTERMEDIARY_OF]->(BEZ1:Entity)
WHERE BEZ1.address CONTAINS "Belize" AND
NOT ((BEZ1.countries="Belize" AND BEZ2.countries="Belize" AND BEZ3.countries="Belize") OR
(BEZ1.status IN ["Inactivated", "Dissolved shelf company", "Dissolved", "Discontinued", "Struck / Defunct / Deregistered", "Dead"]))
SET BEZ4.countries= (BEZ1.countries+","+BEZ2.countries+","+BEZ3.countries)
RETURN BEZ3.countries AS IntermediaryCountries, BEZ3.name AS
Intermediaryname, BEZ2.countries AS OfficerCountries , BEZ2.name AS
Officername, BEZ1.countries as EntityCountries, BEZ1.name AS Companyname,
BEZ1.address AS CompanyAddress,DISTINCT count(BEZ4.countries) AS NoofConnections
The relevant part is the SET statement in the 7th line and the DISTINCT count in the last line. The code shows error which makes no sense to me: Invalid input 'u': expected 'n/N'. I guess it means to use COLLECT probably but we tried that as well and it shows the error vice-versa'd between 'u' and 'n'. Please help us obtain the output that we want, it makes our job hell lot easy. Thanks in advance!
EDIT: Considering I didn't define variable as suggested by #Cybersam, I tried the command CREATE as following but it shows the error "Invalid input 'R':" for the command RETURN. This is unfathomable for me. Help really needed, thank you.
CODE 2:
MATCH (BEZ2:Officer)-[:SHAREHOLDER_OF]->(BEZ1:Entity),(BEZ3:Intermediary)-
[:INTERMEDIARY_OF]->(BEZ1:Entity)
WHERE BEZ1.address CONTAINS "Belize" AND
NOT ((BEZ1.countries="Belize" AND BEZ2.countries="Belize" AND
BEZ3.countries="Belize") OR
(BEZ1.status IN ["Inactivated", "Dissolved shelf company", "Dissolved",
"Discontinued", "Struck / Defunct / Deregistered", "Dead"]))
CREATE (p:Connections{countries:
split((BEZ1.countries+";"+BEZ2.countries+";"+BEZ3.countries),";")
RETURN BEZ3.countries AS IntermediaryCountries, BEZ3.name AS
Intermediaryname, BEZ2.countries AS OfficerCountries , BEZ2.name AS
Officername, BEZ1.countries as EntityCountries, BEZ1.name AS Companyname,
BEZ1.address AS CompanyAddress, AS TOTAL, collect (DISTINCT
COUNT(p.countries)) AS NumberofConnections
Lines 8 and 9 are the ones new and to be in examination.
First Query
You never defined the identifier BEZ4, so you cannot set a property on it.
Second Query (which should have been posted in a separate question):
You have several typos and a syntax error.
This query should not get an error (but you will have to determine if it does what you want):
MATCH (BEZ2:Officer)-[:SHAREHOLDER_OF]->(BEZ1:Entity),(BEZ3:Intermediary)- [:INTERMEDIARY_OF]->(BEZ1:Entity)
WHERE BEZ1.address CONTAINS "Belize" AND NOT ((BEZ1.countries="Belize" AND BEZ2.countries="Belize" AND BEZ3.countries="Belize") OR (BEZ1.status IN ["Inactivated", "Dissolved shelf company", "Dissolved", "Discontinued", "Struck / Defunct / Deregistered", "Dead"]))
CREATE (p:Connections {countries: split((BEZ1.countries+";"+BEZ2.countries+";"+BEZ3.countries), ";")})
RETURN BEZ3.countries AS IntermediaryCountries,
BEZ3.name AS Intermediaryname,
BEZ2.countries AS OfficerCountries ,
BEZ2.name AS Officername,
BEZ1.countries as EntityCountries,
BEZ1.name AS Companyname,
BEZ1.address AS CompanyAddress,
SIZE(p.countries) AS NumberofConnections;
Problems with the original:
The CREATE clause was missing a closing } and also a closing ).
The RETURN clause had a dangling AS TOTAL term.
collect (DISTINCT COUNT(p.countries)) was attempting to perform nested aggregation, which is not supported. In any case, even if it had worked, it probably would not have returned what you wanted. I suspect that you actually wanted the size of the p.countries collection, so that is what I used in my query.
I recently started checking new Java 8 features.
I've come across this forEach iterator-which iterates over the Collection.
Let's take I've one ArrayList of type <Integer> having values= {1,2,3,4,5}
list.forEach(i -> System.out.println(i));
This statement iteates over a list and prints the values inside it.
I'd like to know How am I going to specify that I want it to iterate over some specific values only.
Like, I want it to start from 2nd value and iterate it till 2nd last value. or something like that- or on alternate elements.
How am I going to do that?
To iterate on a section of the original list, use the subList method:
list.subList(1, list.length()-1)
.stream() // This line is optional since List already has a foreach method taking a Consumer as parameter
.forEach(...);
This is the concept of streams. After one operation, the results of that operation become the input for the next.
So for your specific example, you can follow #Joni's command. But if you're asking in general, then you can create a filter to only get the values you want to loop over.
For example, if you only wanted to print the even numbers, you could create a filter on the streams before you forEached them. Like this:
List<Integer> intList = Arrays.asList(1,2,3,4,5);
intList.stream()
.filter(e -> (e & 1) == 0)
.forEach(System.out::println);
You can similarly pick out the stuff you want to loop over before reaching your terminal operation (in your case the forEach) on the stream. I suggest you read this stream tutorial to get a better idea of how they work: http://winterbe.com/posts/2014/07/31/java8-stream-tutorial-examples/
So I followed the directions that I was given to me in my live lecture word for word and also researched this in my textbook and I've done everything (So I think) properly but I keep getting a error Which I have looked up to see what it means and it didn't help me at all and I've been working on it for a whole day so I'm reaching out to you guys to see if you can see my mistake anywheres in my code
This is the question that I am trying to complete:
Using the BOOK_CUSTOMER table and the NVL function, create a query that will return a list containing the customer number, first name, last name, and the characters ‘NOT REFERRED’ if the customer was not referred by another customer. Give the derived column an alias of REFERRED BY. Do not list any customers that were referred by another customer.
MY CODE =
SELECT CutomerID, FirstName, LastName,
NVL(TO_CHAR(Referred), 'Not Referred'))
FROM Book_Customer;
I also realize that I haven't completed the whole question. I'm just trying to get my NVL to work first and then go onto the Alias and the last part of the question because I do not know how to do either of those yet, any tips on that would be greatly appreciated as well
There's an extra (unmatched) closing paren in your SQL text, and that's going to throw a syntax error.
NVL(TO_CHAR(Referred), 'Not Referred'))
^
There's no matching opening paren for that last paren.
To assign an alias to an expression in the SELECT list, follow the expression with the keyword AS and an alias.
SELECT t.foo AS bar
The resultset will contain a column named bar.
SELECT b.CustomerID
, b.FirstName
, b.LastName
, NVL(TO_CHAR(b.Referred),'Not Referred') AS ReferredBy
FROM Book_Customer b
WHERE b.Referred IS NULL
I finally figured it out! The proper code was:
SELECT CustomerID, FirstName, LastName,
NVL(TO_CHAR(Referred), 'Not Referred') AS "Referred By"
FROM Book_Customer
WHERE Referred IS NULL;
Thank you everyone for all your helpful comments that helped me figure out this problem.
I am trying example provided in Graph Databases book (PDF page 51-52)with Neo4j 2.0.1 (latest). It appears that I cannot just copy paste the code sample from the book (I guess the syntax is no longer valid).
START bob=node:user(username='Bob'),
charlie=node:user(username='Charlie')
MATCH (bob)-[e:EMAILED]->(charlie)
RETURN e
Got #=> Index `user` does not exist.
So, I tried without 'user'
START bob=node(username='Bob'),
charlie=node(username='Charlie')
MATCH (bob)-[e:EMAILED]->(charlie)
RETURN e
Got #=> Invalid input 'u': expected whitespace, an unsigned integer, a parameter or '*'
Tried this but didn't work
START bob=node({username:'Bob'}),
(charlie=node({username:'Charlie'})
MATCH (bob)-[e:EMAILED]->(charlie)
RETURN e
Got #=> Invalid input ':': expected an identifier character, whitespace or '}'
I want to use START then MATCH to achieve this. Would appreciate little bit of direction to get started.
From version 2.0 syntax has changed.
http://docs.neo4j.org/chunked/stable/query-match.html
Your first query should look like this.
MATCH (bob {username:'Bob'})-[e:EMAILED]->(charlie {username:'Charlie'})
RETURN e
The query does not work out of the box because you'll need to create the user index first. This can't be done with Cypher though, see the documentation for more info. Your syntax is still valid, but Lucene indexes are considered legacy. Schema indexes replace them, but they are not fully mature yet (e.g. no wildcard searches, IN support, ...).
You'll want to use labels as well, in your case a User label. The query can be refactored to:
MATCH (b:User { username:'Bob' })-[e:EMAILED]->(c:User { username:'Charlie' })
RETURN e
For good performance, add a schema index on the username property as well:
CREATE INDEX ON :User(username)
Start is optional, as noted above. Given that it's listed under the "deprecated" section in the Cypher 2.0 refcard, I would try to avoid using it going forward just for safety purposes.
However, the refcard does state that you can prepend your Cypher query with "CYPHER 1.9" (without the quotes) in order to make explicit use of the older syntax.
I have a column pointsAwarded decimal(9,3) and I have the following LInq
db.TableName.Select(x=>x.pointsAwarded >0)
The fact is that it is not filtering the data and returning me the whole result set.
How to compare it?
I tried with x.pointsAwarded.value>0 and x.pointsAwarded.value>0.000 and
x.pointsAwarded > (Decimal?)0
but with no luck.
Pls help
Try using a Where instead of a Select
db.TableName.Where(x=>x.pointsAwarded > 0)
UPDATE:
This answer has been given more credit than it previously deserved, so I will elaburete a little
The Where statement acts as the filter. It determins whitch elements the returned list should contain.
The Select statement is the projection of the elements. Given a list of elements, how would you like them presented.