Hi,
May be this helps:
set.seed(24)
B101<-
data.frame(SID=sample(400:450,20,replace=FALSE),zGRADE=sample(0:10,20,replace=TRUE),col3=rnorm(20))
set.seed(28)
B2A<-
data.frame(SID=sample(400:600,50,replace=FALSE),zGRADE=sample(0:10,50,replace=TRUE),col3=rnorm(50))
set.seed(35)
B2B<-
data.frame(SID=sample(400:600,50,replace=FALSE),zGRADE=sample(0:10,50,replace=TRUE),col3=rnorm(50))
set.seed(45)
B2C<-
data.frame(SID=sample(400:600,120,replace=FALSE),zGRADE=sample(0:10,120,replace=TRUE),col3=rnorm(120))
Master<- data.frame(SID=400:600)
library(plyr)
Master1<-join_all(list(Master,B101[,1:2],B2A[,1:2],B2B[,1:2],B2C[,1:2]),by="SID")
colnames(Master1)[-1]<- c("B101","B2A","B2B","B2C")
head(Master1,3)
# SID B101 B2A B2B B2C
#1 400 NA 8 NA 3
#2 401 6 NA NA 9
#3 402 NA NA 5 NA
tail(Master1,3)
# SID B101 B2A B2B B2C
#199 598 NA NA NA NA
#200 599 NA NA NA 8
#201 600 NA 2 NA 4
A.K.
----- Original Message -----
From: Robert Lynch <robert.b.ly...@gmail.com>
To: r-help@r-project.org
Cc:
Sent: Tuesday, June 18, 2013 8:16 PM
Subject: [R] data selection
I have two different data frames ( actually a set of data frames for each
class and one master one into which i want pull some data from each of the
frame in the set)
one is all students that have taken a course
so the set of data frames is
B101
B2A
B2B
B2C
etc. . .
and each one has lots of data e.g.
B101
SID zGRADE
444 -.2
458 0
587 .2
etc
and
Master
SID
587
etc
and I would like to make a field in master for each data frame
e.g. Master$B101, Master$B2A
and populate it with the zGrades from each of the data frames
the SID in Master are a wholely containted sub set of the ones in each of
the other data frames
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
