In the pig example:
A = LOAD 'student.txt' AS (name:chararray, term:chararray, gpa:float);
DUMP A;
(John,fl,3.9F)
(John,wt,3.7F)
(John,sp,4.0F)
(John,sm,3.8F)
(Mary,fl,3.8F)
(Mary,wt,3.9F)
(Mary,sp,4.0F)
(Mary,sm,4.0F)
B = GROUP A BY name;
DUMP B;
(John,{(John,fl,3.9F),(John,wt,3.7F),(John,sp,4.0F),(John,sm,3.8F)})
(Mary,{(Mary,fl,3.8F),(Mary,wt,3.9F),(Mary,sp,4.0F),(Mary,sm,4.0F)})
C = FOREACH B GENERATE A.name, AVG(A.gpa);
DUMP C;
({(John),(John),(John),(John)},3.850000023841858)
({(Mary),(Mary),(Mary),(Mary)},3.925000011920929)
The last output A.name is a bag. How can I get things out of bag:
(John, 3.850000023841858)
(Mary, 3.925000011920929)
GROUP creats a magical item called group, which is what you grouped on. This is made for exactly this purpose.
B = GROUP A BY name;
C = FOREACH B GENERATE group AS name, AVG(A.gpa);
Check out DESCRIBE B;, you'll see that group is in there. It is a single value that represents what was in the BY ... part of the GROUP.
Related
Need help with discarding nulls in the result of full outer join in pig Latin. Below are two data sets :
A:
(BOS,2)
(BUR,81)
(LAS,8)
B:
(BUR,56)
(EWR,2)
(LAS,88)
After full outer join :
C :
(BOS,2,,)
(BUR,81,BUR,56)
(,,EWR,2)
(LAS,8,LAS,88)
I need to get the output in below format :
(BOS,2)
(BUR,137)
(EWR,2)
(LAS,96)
Tried different combinations of group by , flatten , bagtotuple ... but was not able to figure out the solution . Many thanks for help.
airline = load '/demo/data/airline/airline.csv' using PigStorage(',') as (Origin: chararray, Dest: chararray);
traffic_in = GROUP airline by Origin;
traffic_in_count= FOREACH traffic_in generate group as Origin , COUNT(airline) as count ;
traffic_out = GROUP airline by Dest;
traffic_out_count = FOREACH traffic_out generate group as Dest ,COUNT (airline) as count;
traffic_top = JOIN traffic_in_count by Origin FULL OUTER , traffic_out_count by Dest ;
EDIT
Instead of using OUTER JOIN use UNION and then SUM the 2nd column values.
A = LOAD 'test1.txt' using PigStorage(',') as (A1:chararray, A2:int);
B = LOAD 'test2.txt' using PigStorage(',') as (B1:chararray, B2:int);
C = UNION A,B;
D = GROUP C BY $0;
E = FOREACH D GENERATE group,SUM(C.$1);
DUMP E;
Output
I have these data that I need to group by two columns and then sum up two other fields.
Suppose the name for these four columns are:OS,device,view,click. I basically want to know the count for each OS and device, how many views they have and how many clicks it have.
(2,3346,1,)
(3,3953,1,1)
(25,4840,1,1)
(2,94840,1,1)
(14,0526,1,1)
(37,4864,1,)
(2,7353,1,)
This is what I have so far
A is data: OS,device,view,click
B = GROUP A BY (OS,device);
Result = FOREACH B {
GENERATE group AS OS,device, SUM(view) AS visits, SUM(click) AS clicks;};
dump Result;
This one won't work, error message is: Projected field [OS] does not exist in schema: group:tuple(OS:int,device:long),B:bag{:tuple(OS:int,device:long,view:int,click:int)}.
Here is the code which is tested, you are missing FLATTEN:
A = LOAD '/user/root/pig_data' using PigStorage(',') AS (OS, device, view, click);
B = GROUP A BY (OS, device);
RESULT = FOREACH B GENERATE FLATTEN(group) AS (OS, device), SUM(A.view) as views, SUM(A.click) as clicks;
dump RESULT;
I think you meant B in your example instead of J2 or J3, which may be in your actual code. Try:
B = GROUP A BY (OS, device);
Result = FOREACH B GENERATE
group.OS AS OS:int,
group.device AS device:long,
SUM(B.view) AS visits:int,
SUM(B.click) AS clicks:int;
dump Result;
I have been trying to find the union_map() equivalent in pig. I know for sure that TOMAP function brings in MAP datatype.
But the requirement is to bring all the MAPs for a given id as shown below.
select I1,UNION_MAP(MAP(Key,Val)) as new_val group by I1;
Sample Input and result is provided below.
Input
ID,Key,Val
ID1,K1,V1
ID2,K1,V2
ID2,K3,V3
ID1,K2,V4
ID1,K1,V7
select ID,UNION_MAP(TO_MAP(Key,VAL)) from table group by ID;
Result
ID1,(K1#V7,K2#V4)
ID2,(K1#V2,K3#V3)
I would like to get the similar output in pig.
Download the piggybank.jar from this link http://www.java2s.com/Code/Jar/p/Downloadpiggybankjar.htm and set it in your classpath and try the below approach.
input
ID1,K1,V1
ID2,K1,V2
ID2,K3,V3
ID1,K2,V4
ID1,K1,V7
PigScript:
REGISTER '/tmp/piggybank.jar';
A = LOAD 'input' USING PigStorage(',') AS (ID:chararray,Key:chararray,Val:chararray);
B = RANK A;
C = GROUP B BY (ID,Key);
D = FOREACH C {
sortByRank = ORDER B BY rank_A DESC;
top1 = LIMIT sortByRank 1;
GENERATE FLATTEN(top1);
}
E = GROUP D BY top1::ID;
F = FOREACH E {
ToMap = FOREACH D GENERATE TOMAP(top1::Key,top1::Val);
GENERATE group,BagToTuple(ToMap) AS myMap;
}
DUMP F;
Output:
(ID1,([K1#V7],[K2#V4]))
(ID2,([K1#V2],[K3#V3]))
I have a table which contain sample CDR data in that column A and column B having calling person and called person mobile number
I need to find whose having maximum number of calls made(column A)
and also need to find to which number(column B) called most
the table structure is like below
calling called
889578226 77382596
889582256 77382596
889582256 7736368296
7785978214 782987522
in the above table 889578226 have most number of outgoing calls and 77382596 is most called number in such a way need to get the output
in hive i run like below
SELECT calling_a,called_b, COUNT(called_b) FROM cdr_data GROUP BY calling_a,called_b;
what might be the equalent code for the above query in pig?
Anas, Could you please let me know this is what you are expecting or something different?
input.txt
a,100
a,101
a,101
a,101
a,103
b,200
b,201
b,201
c,300
c,300
c,301
d,400
PigScript:
A = LOAD 'input.txt' USINg PigStorage(',') AS (name:chararray,phone:long);
B = GROUP A BY (name,phone);
C = FOREACH B GENERATE FLATTEN(group),COUNT(A) AS cnt;
D = GROUP C BY $0;
E = FOREACH D {
SortedList = ORDER C BY cnt DESC;
top = LIMIT SortedList 1;
GENERATE FLATTEN(top);
}
DUMP E;
Output:
(a,101,3)
(b,201,2)
(c,300,2)
(d,400,1)
I need help with this pig script. I am just getting a single record. I am selecting 2 columns and doing a count(distinct) on another while also using a where like clause to find a particular description (desc).
Here's my sql with pig I am trying to code.
/*
For example in sql:
select domain, count(distinct(segment)) as segment_cnt
from table
where desc='ABC123'
group by domain
order by segment_count desc;
*/
A = LOAD 'myoutputfile' USING PigStorage('\u0005')
AS (
domain:chararray,
segment:chararray,
desc:chararray
);
B = filter A by (desc=='ABC123');
C = foreach B generate domain, segment;
D = DISTINCT C;
E = group D all;
F = foreach E generate group, COUNT(D) as segment_cnt;
G = order F by segment_cnt DESC;
You could GROUP on each domain and then count the number of distinct elements in each group with a nested FOREACH syntax:
D = group C by domain;
E = foreach D {
unique_segments = DISTINCT C.segment;
generate group, COUNT(unique_segments) as segment_cnt;
};
You can better define this as a macro:
DEFINE DISTINCT_COUNT(A, c) RETURNS dist {
temp = FOREACH $A GENERATE $c;
dist = DISTINCT temp;
groupAll = GROUP dist ALL;
$dist = FOREACH groupAll GENERATE COUNT(dist);
}
Usage:
X = LOAD 'data' AS (x: int);
Y = DISTINCT_COUNT(X, x);
If you need to use it in a FOREACH instead then the easiest way is something like:
...GENERATE COUNT(Distinct(x))...
Tested on Pig 12.
If you don't want to count on any group, you use this:
G = FOREACH (GROUP A ALL){
unique = DISTINCT A.field;
GENERATE COUNT(unique) AS ct;
};
This will just give you a number.