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Let's say I have two objects in my environment, obj_1 and obj_2. And I also have a vector of their names vec <- c("obj_1", "obj_2").
Now, I want to exclude something from that vector, let's say vec <- vec[-c(2)], and then to pass the rest to another custom function -- i.e. somehow paste the vector contents the way that it would correspond to an actual object in an my environment.
How can it be done?
Set up your environment:
obj_1 <- 1:10
obj_2 <- 11:20
vec <- c("obj_1", "obj_2")
Get the name of the object that you want:
vec <- vec[-2]
Get the object:
get(vec)
Also look at mget
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If I have multiple data.frame in my environment with name _OK, and I would like add ID=1 into each of them. Is it a way that i can do it at once instead of one by one? I know that i can use mget to build a list for the data.frame ended with _OK. But I would like to know whether there is a way to skip the list. USing list, I will be ended up with two set of data.
Any suggestion?
We could do that in a for loop with assign
for(obj in ls(pattern = '_OK')) {
tmp <- get(obj)
tmp$ID <- 1
assign(obj, tmp)
}
Or another option is mget to return the datasets into a list, transform each element by looping over the list and update the objects in the global environment with list2env
list2env(lapply(mget(ls(pattern = '_OK')), transform, ID = 1), .GlobalEnv)
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I need to change column in many files. I have files in which my names in ID column are written wrong. I prepared excel files with 2 columns "wrong ID" and "new ID" and now I want to change it in every files.
for ex.
wrong ID new ID
CALU1 calu-1
I have almost 300 different ID.
We can keep the files in a list after reading them and then use rename_at
library(dplyr)
lst1 <- lapply(files, function(x) {
x1 <- read.csv(x)
x1 %>%
rename_at(vars(df$`wrong ID`), ~ df$`new ID`)
})
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I have a code,and i am going to do a for loop on two gamma distributions.
Given the list of shape parameter, and i name them "d" then i put in d[1] and d[2] in the random gamma function.
I have simplified what I wish to ask here. when i code d[1] in R, output will be the first vector,while when i code d[2] in R, output will be the second vector.
I have a bit lose then how will it iterate if i using for loop for d ?
*
List_1 <- list(c(4,16),c(16/9,4),c(1,16/9),c(.64,1),c(4/9,.64))
for ( d in List_1) ##first parameter is for gamma.1, second is for gamma.2
{
x<-rgamma(25,d[1],1)
y<-rgamma(25,d[2],1)
t<-t.test(x,y)$p.value
}*
I am sorry if i do ask a silly question. Thanks in advance.
In R it is better to avoid for loops due to their poor performance. Since you are starting with a list lapply is a good start:
lapply(List_1, FUN=function(x){t.test(rgamma(25,x[1],1), rgamma(25,x[2],1))$p.value})
The apply function takes your list and then uses the gamma function on the 2 parameters within the t.test. The result will be a list of the five p values, one for each pair
Your code runs fine. I am actually not sure what you are asking here. You can just use print to find the iteratives, if that is what you want, like:
for (d in List_1){
print(d[1])
print(d[2])
}
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This is a very simple problem and I'll probably catch flame for asking this, but I've looked everywhere and I can't find the answer... Or a different approach to my code.
I need to remove the first row of a data frame if the value of the first row and third column are equal to one.
This is what I have so far:
if (foo[1, 3] == 1) {
foo <- foo[-1, ]
}
Is there a different way to do this using only bracket subsetting (avoiding using an if statement)?
Edit:
Edited for clarity.
The code you wrote doesn't remove the first row permanently, it only prints it out. Change that with foo<-foo[-1, ]
Additionally, the code within the if-statement brackets is only one line anyway, you don't technically need them, but some like them for clarity purposes
if (foo[1, 3] == 1) foo <- foo[-1, ]
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I want to paste 4 strings together, the code is here:
urlstring<-"lee/"
code<-read.csv("D:\\list.csv",sep="\n",head=FALSE)
for(y in code){count<-1
while(count<3){
mydate<-Sys.Date()-count
filename<-paste(urlstring,mydate,"&symbol=",y,sep="")
print(filename)
count<-count+1
}
}
my question is why the output is, date is changing firstly :
lee/date=2013-11-14&symbol=1
lee/date=2013-11-14&symbol=2
lee/date=2013-11-13&symbol=1
lee/date=2013-11-13&symbol=2
but in my opinion,the result should be this,the value of code should be changed firstly:
lee/date=2013-11-14&symbol=1
lee/date=2013-11-13&symbol=1
lee/date=2013-11-14&symbol=2
lee/date=2013-11-13&symbol=2
Like #mnel said. for code = 1:2 your code yields the correct results. Note that the nested for-while loop is not needed, a vectorized solution uses less code is and is often faster:
code = rep(1:2, each = 2)
mydate = Sys.Date() - code
sprintf('lee/date=%s&symbol=%d', mydate, code)
[1] "lee/date=2013-11-14&symbol=1" "lee/date=2013-11-14&symbol=1"
[3] "lee/date=2013-11-13&symbol=2" "lee/date=2013-11-13&symbol=2"
This solution is called vectorized because when sprintf is used with vectors, the result is also a vector, without explicitily using a loop.