Hi,
Possibly, FAQ 7.31
Using the same example:
set.seed(24)
df<- data.frame(x=sample(seq(0.25,4.25,by=.05),1e5,replace=TRUE),y=
sample(seq(0.10,1.05,by=.05),1e5,replace=TRUE),z=rnorm(1e5))
dfOld<- df
df[,1:2]<- lapply(df[,1:2],function(x) sprintf("%.2f",x))
x1<- c(1.05,2.85,3.40,4.25,0.25)
y1<- c(0.25,0.10,0.90,0.25,1.05)
x1New<-sprintf("%.2f",x1)
y1New<- sprintf("%.2f",y1)
res1<-do.call(rbind,lapply(seq_along(x1New),function(i)
subset(df,x==x1New[i]&y==y1New[i])))
res<-do.call(rbind,lapply(seq_along(x1),function(i)
subset(dfOld,x==x1[i]&y==y1[i])))
dim(res1)
#[1] 318 3
dim(res)
#[1] 250 3
res1[,1:2]<- lapply(res1[,1:2],as.numeric)
str(res1)
#'data.frame': 318 obs. of 3 variables:
# $ x: num 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 1.05 ...
# $ y: num 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 ...
# $ z: num 0.787 -1.568 -1.626 -0.221 -0.7 ...
A.K.
nevermind.... error on my behalf got it going.
I have another issue, it leaves some values out. ive seperately
searched the df and theyre definitely in there... so it there some sort
of exclusion rule? there are about 8 of the 28 missing... the first row
missing is 3.05,1.70 . i looked up the documentation for subset but i
cant see why it would skip ones...
thanks
----- Original Message -----
From: arun <smartpink...@yahoo.com>
To: R help <r-help@r-project.org>
Cc:
Sent: Wednesday, July 3, 2013 7:37 AM
Subject: Re: Subsetting multiple rows of a data frame at once
Hi,
Try this:
set.seed(24)
df<- data.frame(x=sample(seq(0.25,4.25,by=.05),1e5,replace=TRUE),y=
sample(seq(0.10,1.05,by=.05),1e5,replace=TRUE),z=rnorm(1e5))
#Used a shorter vector
x1<- c(1.05,2.85,3.40,4.25,0.25)
y1<- c(0.25,0.10,0.90,0.25,1.05)
res<-do.call(rbind,lapply(seq_along(x1),function(i)
subset(df,x==x1[i]&y==y1[i])))
head(res,2)
# x y z
#466 1.05 0.25 0.7865224
#4119 1.05 0.25 -1.5679096
tail(res,2)
# x y z
#98120 0.25 1.05 -2.1239596
#98178 0.25 1.05 0.3321464
A.K.
Hi Everyone,
First time poster so any posting rules i should know about feel free to
advise...
I've got a data frame of 250 000 rows in columns of x y and z.
i need to extract 20-30 rows from the data frame with specific x
and y values, such that i can find the z value that corresponds. There
is no repeated data. (its actually 250 000 squares in a 5x5m grid)
to find them individually i can use subset successfully
result<-subset(df,x==1.05 & y==c0.25)
gives me the row in the dataframe with that x and y value.
so if i have
x = 1.05 2.85 3.40 4.25 0.25 3.05 3.70 0.20 0.30 0.70 1.05 1.20
1.40 1.90 2.70 3.25 3.55 4.60 2.05 2.15 3.70 4.85 4.90 1.60 2.45 3.20
3.90 4.45
and
y= 0.25 0.10 0.90 0.25 1.05 1.70 2.05 2.90 2.35 2.60 2.55 2.15
2.75 2.05 2.70 2.25 2.55 2.05 3.65 3.05 3.00 3.50 3.75 4.85 4.50 4.50
3.35 4.90
then how can i retrieve the rows for all those values at once.
if i name x=xt and y=yt and then
result<-subset(df,x==xt & y==yt)
then i get
result
[1] x y Height
<0 rows> (or 0-length row.names)
i dont understand why zero rows are selected. obviously im
applying the vectors inappropriately, but i cant seem to find anything
on this method of subsetting online.
Thanks for any replies!
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