news()

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Here’s how to use news() function.

A.news( X;xi:Fi,… )

Description:

Compute each member of a sequence according to the specified condition to generate multiple records and concatenate them into a new table sequence.

Syntax:

A.news(X;xi:Fi,…)

Note:

 The function computes expression xi on each member of sequence A and sequence/integer X, generate multiple records and concatenate them to generate a new table sequence.

Parameter:

A

A sequence

X

A sequence/integer; can be understood as to(X) when it is an integer, meaning performing X number of computations on sequence A

xi

An expression, whose results will be field values; the sign ~ used in the parameter references data from X instead of A

Fi

Field name of the result sequence; when omitted, field names are xi by default, and use the original field names when xi is #i

Option:

@1

Left join, which creates an empty record when X is empty; here it is number 1 instead of letter l

@m

Use parallel processing to increase performance

Return value:

A table sequence

Example:

When A is a sequence

 

A

 

1

[1,2,3,4,5]

 

2

=A1.news([10,20]; A1.~:a,~:b,a*b)

Parameter X is a sequence and compute members of A and X one by one, that is, use A1’s members as values of field a, members of [10,20] as values of field b and result values of a*b as values of the 3rd field; as parameter Fi is absent, use parameter xi as field names

3

=A1.news(2; A1.~:a, ~:b,a*b)

Parameter X is an integer, which is equivalent to to(2), and compute each of A1’s member two times

 

When A is a table sequence

 

A

 

1

=demo.query("select top 5 ID,NAME,BIRTHDAY,DEPT,SALARY from EMPLOYEE")

2

=A1.news(~;NAME,age(BIRTHDAY):AGE)

Parameter X is a table sequence and symbol ~ is understood as member of A1; compute A1 and return records consisting of NAME field and AGE field, where AGE field is computed from A1’s BIRTHDAY field

3

=A1.news(3;EID,NAME,SALARY*~:Salary)

Parameter X is integer 3 and compute each member of A1 three times; ~ is understood as the current number of computations

 

A为排列

 

A

 

1

=demo.query("select top 10 EID,NAME,DEPT,GENDER,SALARY from EMPLOYEE")

2

=A1.group(DEPT).(~.group(GENDER))

Group table sequence A1 by DEPT and then group the result by GENDER

3

=A2.news(~;A2.~.DEPT,A2.~.~.GENDER,A2.~.~.avg(SALARY):AvgSalary)

Get DEPT and GENDER values from A2’s group and calculate average salary of each GENDER in each DEPT

 

When parameter xi uses #i

 

A

 

1

=demo.query("select  top 10  EID,NAME,BIRTHDAY,GENDER,SALARY from EMPLOYEE")

2

=A1.group(GENDER;~:GenderGroup,~.avg(SALARY):Avg)

Group A1 by GENDER and calculate average salary in each group

3

=A2.news(GenderGroup;EID,#2,GENDER, age(~.BIRTHDAY):age,SALARY+1000:Nsalary,A2.Avg:AvgSalary)

Compute the expression on each group of A2 and generate records to form a new table sequence, during which #2 represents NAME, the 2nd field of GenderGroup

 

Use @1 option to perform left join

 

A

 

1

=demo.query("select top 5 EID,NAME,BIRTHDAY,GENDER,SALARY from EMPLOYEE")

2

=A1.group(GENDER;~:GenderGroup)

Group A1’s records by GENDER

3

=demo.query("select top 10 EID,NAME,BIRTHDAY,GENDER,SALARY from EMPLOYEE")

4

=A3.group(GENDER;avg(SALARY):avg)

Group A3 by GENDER and calculate average salary in each group

5

=A4.join(GENDER,A2:GENDER,GenderGroup)

Perform association between A2 and A4 according to GENDER field; since A2 does not have records where GENDER is M, the corresponding GenderGroup field values are represented by nulls after table association

6

=A5.news(GenderGroup;EID,NAME,GENDER,age(~.BIRTHDAY):age,avg:AvgSalary)

Compute the expression on record sequence A5 to generate new records, from which those whose GenderGroup is empty are by default discarded

7

=A5.news@1(GenderGroup;EID,NAME,GENDER,age(~.BIRTHDAY):age,avg:AvgSalary)

Use @1 option to create an empty record when record sequence X is empty

Related function:

cs.news()

ch.news()

Description:

Get new values for the fields of records in a channel and update them into the channel.

Syntax:

ch.news(X;xi:Fi,…)

Note:

With channel ch, the function computes values of fields in record sequence X and updates the new field values into the channel. Fi is the new field name that will be automatically identified if the parameter is omitted; xi represents the new field values. This is an attached computation.

Parameter:

ch

Channel

X

Record sequence

xi

Expression, whose results will be field values; the sign ~ used in the parameter references data from X instead of A. The sign # is used to represent a field with a ordinal number

Fi

Field name in the given channel; will be automatically identified if the parameter is omitted

Return value:

Channel

Example:

 

A

 

1

=demo.cursor("select * from EMPLOYEE")

 

2

=demo.query("select * from EMPLOYEE")

 

3

=channel()

Create a channel

4

=A2.group(GENDER;~:group)

Group records by GENDER

5

=A1.groupx(GENDER;avg(SALARY):avg)

Group records by GENDER

6

=A5.join(GENDER,A4:GENDER,group)

 

7

=A3.news(group;EID,NAME,GENDER,#3:surname, age(~.BIRTHDAY):age,SALARY+50: salary,avg:AvgSalary)

A6 is one of the groups; compute field values based on each group and concatenate the results into A3’s channel

8

=A3.fetch()

Fetch and store the existing data in the channel

9

=A6.push(A3)

Be ready to push data in A6’s cursor into A3’s channel, but the action needs to wait

10

=A6.fetch()

Data in A6’s cursor is pushed into the channel and operations are performed as the fetch() operation is performed over A6

11

=A3.result()

cs.news()

Description:

Generate multiple records based on a record sequence, concatenate them into a new table sequence and return it to the original cursor.

Syntax:

cs.news(X;xi:Fi,…)

Note:

The function attaches a computation to cursor cs, which computes expression xi on record sequence X , makes the results values of the new field Fi, and generates multiple records to form a new table sequence, and returns the table sequence to the original cursor cs.

This is a delayed function.

Parameter:

cs

A cursor

X

Record sequence

xi

An expression, whose values are uses as the new field values. It is treated as null if omitted; in that case, : Fi can’t be omitted. The sign # is used to represent a field with a ordinal number

Fi

Filed name of the new cs; use the identifiers parsed from expression xi if it is omitted

Option:

@1  Left join, which creates an empty record when record sequence X is empty

Return value:

Cursor

Example:

 

A

 

1

=demo.cursor("select EID,NAME,DEPT,GENDER,BIRTHDAY,SALARY from EMPLOYEE")

Return a cursor.

 

2

=demo.query("select EID,NAME,DEPT,GENDER,BIRTHDAY,SALARY from EMPLOYEE")

Return a table sequence:

3

=A2.group(GENDER;~:gup)

Group table sequence A2 by GENDER field and return result set as follows:

4

=A1.groupx(GENDER;avg(SALARY):avg)

Group cursor A1 by GENDER field, compute average SALARY value in each group and return a cursor; below is data in the result cursor:

5

=A4.join(GENDER,A3:GENDER,gup)

Attach a computation to cursor A4, which performs foreign key join with A3 and return the original cursor A4; below is the data of cursor A4 where A5’s computation is executed:

6

=A4.news(gup;EID,#2:Lname,GENDER,age(~.BIRTHDAY):Age,SALARY+50: Salary,avg:AvgSalary)

Attach a computation to cursor A4 to compute gup field values, renames the 2nd field Lname using expression #2Lname, form a table sequence consisting of EID, Lname, GENDER, Age, Salary and AvgSalary to return cursor A4, and returns the original cursor.

7

=A4.fetch()

Fetch data from cursor A4 where A6’s computation is executed (it would be better to fetch data in batches when a huge amount of data is involved):

 

When @1 option works:

 

A

 

1

=demo.cursor("select  EID,NAME,DEPT,GENDER,BIRTHDAY,SALARY from EMPLOYEE")

Return a cursor.

 

2

=demo.query("select EID,NAME,DEPT,GENDER,BIRTHDAY,SALARY from EMPLOYEE where GENDER='M' ")

Return a table sequence:

3

=A2.group(GENDER;~:gup)

Group table sequence A2 by GENDER field and return result set as follows:

4

=A1.groupx(GENDER;avg(SALARY):avg)

Group cursor A1 by GENDER field, compute average SALARY value in each group and return a cursor; below is data in the result curso

5

=A4.join(GENDER,A3:GENDER,gup)

Attach a computation to cursor A4, which performs foreign key join with A3 and returns the original cursor A4; below is data in cursor A4 where the attached computation is executed:

6

=A4.news@1(gup;EID,NAME,GENDER,age(~.BIRTHDAY):Age,Salary,avg:AvgSalary)

Attach a computation to cursor A4 to compute gup field values, form a table sequence consisting of EID, NAME, GENDER, Age, Salary and AvgSalary to return cursor A4, and returns the original cursor. @1 option enables left join to create an empty record when the corresponding record in record sequence X is empty.

7

=A4.fetch()

Fetch data from cursor A4 where A6’s computation is executed; below is the result set:

 

Related functions:

A.news(X;xi:Fi,…)

T.news( A/cs,K,x:C,…;wi,... )

Description:

 Return a table sequence/cursor consisting of the specified fields according to the correspondence between the table sequence/cursor’s key and the corresponding field in the composite table.

Syntax:

T.news(A/cs:K,x:C,…;wi,...)

Note:

 Composite table T is the subtable and table sequence/cursor A/cs is the primary table. They have a many-to-one relationship. The function matches A/cs’s key (/dimension) field with the corresponding fields of T (begin the correspondence from the first field) and returns a table sequence/cursor made up of x:C fields. It is required that A/cs be ordered by the key (/dimension) and the key (/dimension) has the same order as T’s first field.

With a table sequence parameter, the function returns a table sequence, and with a cursor parameter, it returns a cursor or a multicursor.

Align the returned result set to T and set key/dimension for it; copy records of the primary table.Parameter:

T

A composite table

A/cs

A table sequence/cursor/composite table cursor

K

 A/cs’s field name; when it is specified, use it to match with T’s first field; when it is absent, use A/cs’s key (/dimension) to perform the matching; when there are multiple Ks, use colon (:) to separate them

x

Field names or aggregate function count/sum/max/min/avg

C

Column alias

wi

Filtering condition on T; retrieve the whole set when this parameter is absent; separate multiple conditions by comma(s) and their relationships are AND. Besides regular filtering expressions, you can also use the following five types of syntax in a filtering condition, where K is a non-key field in entity table T:

1K=w

w usually uses expression Ti.find(K) or Ti.pfind(K), where Ti is a table sequence. When value of w is null or false, the corresponding record in the entity table will be filtered away; when w is expression Ti.find(K) and the to-be-selected fields C,... contain K, Tis referencing field will be assigned to K; when w is expression Ti.pfind(K) and the to-be-selected fields C,... contain K, ordinal numbers of K values in Ti will be assigned to K.

2(K1=w1,Ki=wi,w)

Ki=wi is an assignment expression. Generally, parameter wi can use expression Ti.find(Ki) or Ti.pfind(K), where Ti is a table sequence; when wi is expression Ti.find(Ki) and the to-be-selected fields C,... contain Ki, Ti’s referencing field will be assigned to Ki correspondingly; when wi is expression Ti.pfind(Ki) and the to-be-selected fields C,... contain Ki, ordinal numbers of Ki values in Ti will be assigned to Ki.

w is a filter expression; you can reference Ki in w.

3K:Ti

Ti is a table sequence. Compare Ki value in the entity table with key values of Ti and discard records whose Ki value does not match; when the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K.

4K:Ti:null

Filter away all records that satisfy K: Ti.

Option:

@r  Perform aggregation on data of the subtable and return a result set aligned to A/cs

Return value:

Table sequence/Cursor

Example:

 

A

 

1

=connect("demo").cursor("SELECT STUDENTID,CLASS,SUBJECT,SCORE FROM SCORES")

Return a cursor

2

=file("scores-news.ctx")

 

3

=A2.create@y(#STUDENTID,#CLASS,SUBJECT,SCORE)

Create a composite table and set STUDENTID and CLASS as its dimension

4

=A3.append@i(A1)

5

=connect("demo").query("SELECT ID,NAME,GENDER,AGE FROM STUDENTS")

Return a table sequence

6

=A4.news(A5:ID,CLASS,STUDENTID,NAME,GENDER,SUBJECT,SCORE)

A4 is the subtable and A5 is the primary table; perform the matching according to table sequence A5’s ID field and T’s first key field STUDENTID and return a table sequence consisting of CLASS, STUDENTID, NAME, GENDER, SUBJECT and SCORE fields; copy records of the primary table and return the following result:

7

=A5.keys(ID)

Set ID as table sequence A5’s key

8

=A4.news(A7,CLASS,STUDENTID,NAME,GENDER,SUBJECT,SCORE)

As parameter K is absent, perform the matching according to A7’s key and the composite table’s first key field and return same result as A6

9

=A4.news@r(A7,NAME,GENDER,sum(SCORE):TotalScore)

Use @r option to summarize data in the subtable

10

=A4.news(A7,CLASS,STUDENTID,NAME,GENDER,SUBJECT,SCORE;CLASS=="Class one",SUBJECT=="Math")

Perform filtering on A4’s data according to filter condition: CLASS=="Class one" and SUBJECT=="Math" during association

 

When there are multiple K parameters:

 

A

 

1

=file("sco.ctx").open()

Open a composite table as follows:

2

=file("stu.txt").import@t()

Return a table sequence:

3

=A1.news(A2:Class:StudentID,NAME,SUBJECT,SCORE)

A1 is the subtable and A2 is the primary table; perform the matching between table sequence A2’s Class and StudentID fields and T’s first two fields – Class and StudentID – and return a table sequence consisting of NAME,SUBJECT,SCORE; copy records of the primary table and return the following result:

4

=A1.news@r(A2:Class:StudentID,NAME,sum(SCORE):TotalScore)

Use @r option to summarize data in the subtable

 

 

Use special types of filtering conditions:

 

A

 

1

=demo.cursor("select STUDENTID,CLASS,SUBJECT,SCORE from SCORES")

Below is content of the cursor:

2

=file("scores.ctx")

 

3

=A2.create@y(#STUDENTID,#CLASS,SUBJECT,SCORE )

Create a composite table

4

=A3.append@i(A1)

Append cursor A1’s data to the composite table’s base table

5

=demo.query("select  ID,NAME,GENDER,AGE  from STUDENTS")

Return a table sequence

6

=A3.news(A5:ID,STUDENTID,NAME,SUBJECT,SCORE)

Match the composite table’s key values to table sequence’s fields and retrieve corresponding composite table fields and return a table sequence

7

=create(Subject,Num).record(["PE",01,"Math",02,"History",03]).keys(Subject)

Generate a table sequence using Subject as the key

8

=A3.news(A5:ID,NAME,SUBJECT,SCORE;SUBJECT=A7.find(SUBJECT))

Use K=w filtering mode; in this case w is Ti.find(K) and entity table records making SUBJECT=A7.find(SUBJECT) get null or false are discarded; SUBJECT is the selected field, to which table sequence A7’s referencing field is assigned

9

=A3.news(A5:ID,NAME,SUBJECT,SCORE;SUBJECT=A7.pfind(SUBJECT))

Use K=w filtering mode; in this case w is Ti.pfind(K) and entity table records making SUBJECT=A7.pfind(SUBJECT) get null or false are discarded; SUBJECT is the selected field, to which its ordinal numbers in table sequence A7 are assigned

10

=A3.news(A5:ID,NAME,SUBJECT,SCORE;SUBJECT:A7)

Use K:Ti filtering mode; compare the entity table’s SUBJECT values with the table sequence’s key values and discard entity table records that cannot match

11

=A3.news(A5:ID,NAME,SCORE;SUBJECT:A7)

This is a case where K isn’t selected; SUBJECT isn’t the selected field, so only filtering is performed

12

=A3.news(A5:ID,NAME,SUBJECT,SCORE;SUBJECT:A7:null)

Use K:Ti:null filtering mode; compare the entity table’s SUBJECT values with the table sequence’s key values and discard entity table records that can match

13

=create(Score,Level).record([90,"A",80,"B",70,"C",60,"D"]).keys(Score)

Return a table sequene using Score as the key

14

=A3.news(A5:ID,NAME,SUBJECT,SCORE;(SCORE=A13.find(SCORE),SUBJECT=A7.find(SUBJECT),SCORE!=null&&SUBJECT!=null))

Use (K1=w1,Ki=wi,w) filtring mode; return records that meet all conditions

 

Note: The difference between T.new() and T.news() is that the former works when T and A/cs has a one-to-many relationship and the latter operates when T and A/cs has a many-to-one relationship.