[R] Some SQL Challenges

Don MacQueen macq at llnl.gov
Thu Aug 6 16:21:47 CEST 2009

Don't understand what this has to do with SQL, or why you're asking 
for SQL solutions in an R mailing list, but here are some R 

(abbreviating "COLUMN" with "C")

At 11:40 AM -0700 8/3/09, JoK LoQ wrote:
>Im trying to complete a list of jobs using SQL Querries and some "if else"
>commands but im stucked in some steps. Could any of you give me some help?
>-in COLUMN1 change the format 20JAN2000:00:00:00 to 20JAN2000 and exclude
>every row that date is different from 20.

Assuming C1 contains character strings:
   C1 <- substring( C1, 1, 9)
   C1 <- C1[  substring(C1,1,2) == '20' ]

>-extract the first character in COLUMN2 and creat COLUMN3 with that value

   C3 <- substring( C2, 1 ,1)
   C3 <- as.numeric( substring( C2, 1, 1) )

>-in every row in which COL3=5, value in COLUMN4=value in COLUMN5

C4[ C3==5] <- C5[ C3==5]

>-create COLUMN7 where if COLUMN6="north" then COLUMN7 value="N" else COLUMN7

C7 <- ifelse( C6 == "north" , "N", "X")

>Ill be grateful for any help, thnks
>View this message in context: 
>Sent from the R help mailing list archive at Nabble.com.
>R-help at r-project.org mailing list
>PLEASE do read the posting guide http://*www.*R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.

Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA

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