[R] I had 1 problem with r

[peter dalgaard]

On 22 Aug 2016, at 07:06 , 정수빈 <subincj at naver.com> wrote:

> Hi My name is SuBin-Jung from Korea.
> 
> I can't write english well. so, understand me please.
> 
> I used R Gui(64-bit) program.
> 
> And in program, I imported this csv file named "emp.csv"
> 
> emp.csv
> ---------------------------------------------
> empno,ename,job,mgr,hiredate,sal,comm,deptno
> 7369,SMITH,CLERK,7902,1980-12-17,800,,20
> 7499,ALLEN,SALESMAN,7698,1981-02-20,1600,300,30
> 7521,WARD,SALESMAN,7698,1981-02-03,1250,500,30
> 7566,JONES,MANAGER,7839,1981-03-02,2975,,20
> 7654,MARTIN,SALESMAN,7698,1981-10-22,1250,1400,30
> 7698,BLAKE,MANAGER,7839,1981-05-01,2850,,30
> 7782,CLARK,MANAGER,7839,1981-09-06,2450,,10
> 7788,SCOTT,ANALYST,7566,1982-12-08,3000,,20
> 7839,KING,PRESIDENT,,1981-11-17,5000,,10
> 7844,TURNER,SALESMAN,7698,1984-10-08,1500,,30
> 7876,ADAMS,CLERK,7788,1983-01-12,1100,,20
> 7900,JAMES,CLERK,7698,1981-12-03,950,,30
> 7902,FORD,ANALYST,7566,1981-12-13,3000,,20
> 7934,MILLER,CLERK,7782,1982-01-25,1300,,10
> ----------------------------------------------
> 
> Then I used command "read.csv"  ==> read.csv("emp.csv")
> 
> And I tried to find emp$ename with first alphabet 'A'.
> 
> So I inserted this command on program :
> 
> > subset(emp, ename==grep("^A+",ename,value=TRUE), select=c("ename","sal")) 
> 
> But the result is not found.
> 
> After that I tried to other alphabets( B,S,W....)
> 
> > subset(emp, ename==grep("^S+",ename,value=TRUE), select=c("ename","sal"))
> 


Please do not post in HTML (reason should be pretty obvious).

Your logic is wrong: 

ename==grep("^A+",ename,value=TRUE)

Right hand side evaluates to c("ALLAN","ADAMS"); you then compare this to ename, which by recycling means that you compare 

SMITH to ALLAN, 
ALLAN to ADAMS, 
WARD to ALLAN, 
JONES to ADAMS,
...
TURNER to ADAMS,
ADAMS to ALLAN
...


See?

subset(emp, grepl("^A+",ename), select=c("ename","sal")) 

should work (and is simpler, too)

-pd


> Then I can find two data.
> 
>  ename  sal
> 1 SMITH  800
> 8 SCOTT 3000
> 
> 
> Why can't I find emp$ename with first alphavet 'A'??
> I think this is error. 
> Please give me answer, sir. 
> 
> 	[[alternative HTML version deleted]]
> 
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-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com