This question already has answers here:
Generate an incrementally increasing sequence like 112123123412345
(4 answers)
Closed 1 year ago.
I have a sequence of numbers like this:
> seq(2,6,1)
[1] 2 3 4 5 6
I would like to replicate this sequence and remove one number from the end of the sequence while doing replication. This is what I want to have:
[1] 2 3 4 5 6 2 3 4 5 2 3 4 2 3 2
Is there any functions in R can help me get this sequence?
Thank you very much.
I am sure there is a fancier way, but the following code achieves the goal in base R.
out = integer()
a = 2:6
while( length(a) > 1 ) {
a = a[-length(a)]
out = c(out, a)
}
out
#> [1] 2 3 4 5 2 3 4 2 3 2
Created on 2021-03-18 by the reprex package (v1.0.0)
That should be it:
sequence(5:1, from = 2)
[1] 2 3 4 5 6 2 3 4 5 2 3 4 2 3 2
Related
This question already has answers here:
Repeat each row of data.frame the number of times specified in a column
(10 answers)
Closed 2 years ago.
library(data.table)
dataHAVE=data.frame("student"=c(1,2,3),
"score" = c(10,11,12),
"count"=c(4,1,2))
dataWANT=data.frame("student"=c(1,1,1,1,2,3,3),
"score"=c(10,10,10,10,11,12,12),
"count"=c(4,4,4,4,1,2,2))
setDT(dataHAVE)dataHAVE[rep(1:.N,count)][,Indx:=1:.N,by=student]
I have data 'dataHAVE' and seek to produce 'dataWANT' that basically copies each 'student' 'count' number of times as shown in 'dataWANT'. I try doing this as shown above in data.table as this is the solution I seek but get error
Error: unexpected symbol in "setDT(dat)dat"
and I cannot resolve thank you so much.
Try:
setDT(dataHAVE)[rep(1:.N,count)]
Output:
student score count
1: 1 10 4
2: 1 10 4
3: 1 10 4
4: 1 10 4
5: 2 11 1
6: 3 12 2
7: 3 12 2
As explained you could also replace 1:.N and do setDT(dataHAVE)[dataHAVE[, rep(.I, count)]].
Just FYI, there's also a nice function in tidyr that does similar thing:
tidyr::uncount(dataHAVE, count, .remove = FALSE)
Here is a base R solution
dataWANT<-do.call(rbind,
c(with(dataHAVE,rep(split(dataHAVE,student),count)),
make.row.names = FALSE))
such that
> dataWANT
student score count
1 1 10 4
2 1 10 4
3 1 10 4
4 1 10 4
5 2 11 1
6 3 12 2
7 3 12 2
This question already has an answer here:
Generate a repeating sequence based on vector
(1 answer)
Closed 5 years ago.
I need some help. How to create the following vector sequence:
1 1 1 1 2 2 2 3 3 4
I tried to use (rep) and (seq) but still unsucessfull.
Try this:
rep(1:4,4:1)
Output:
[1] 1 1 1 1 2 2 2 3 3 4
or less concisely: c(rep(1, 4), rep(2,3), rep(3, 2), 4)
output: [1] 1 1 1 1 2 2 2 3 3 4
This question already has answers here:
Counting the number of elements with the values of x in a vector
(20 answers)
Closed 6 years ago.
I have a single row of numbers. I'm wondering how I can separate it out so that it outputs columns that total the tally of each set of numbers. I've tried playing around with "separate" but I can't figure out how to make it work.
Here's my data frame:
2
2
2
2
2
4
4
4
I'd like it to be
2 4
5 3
You can use the table() function.
> df
V1
1 2
2 2
3 2
4 2
5 2
6 4
7 4
8 4
> table(df$V1)
2 4
5 3
We can use tabulate which would be faster
tabulate(factor(df1$V1))
#[1] 5 3
This question already has answers here:
Find and break on repeated runs
(3 answers)
Closed 6 years ago.
Imagine a vector of integers like so:
> rep(c(1,4,2),10)
[1] 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2 1 4 2
For us human beings it seems easy to identify the pattern 1 - 4 - 2 even without knowing the function how the vector was created. But how would you identify this pattern using R?
Edit
As this question was marked as a dupe I'm going to specify it a bit. The above example was an easy one to explain the idea. The main goal would be to identify more hidden patterns like 1 4 2 5 6 7 1 4 2 9 1 4 2 3 4 5 1 4 2 and also patterns that are approximately the same like 1 4 2 1 4 1.99 1 4 2 1.01 4 2 1 4.01 2. What are the ideas to always Identify the pattern 1 4 2 in those cases?
Assuming that the subpattern must start at the beginning and repeat to the end of the input try it for a subpattern length of k = 1, 2, 3, ... We have assumed that only patterns that are half the length of the input or less are to be considered:
for(k in seq_len(length(x)/2)) {
pat <- x[1:k]
if (identical(rep(pat, length = length(x)), x)) {
print(pat)
break
}
}
## [1] 1 4 2
Note: This was used as the input x:
x <- rep(c(1, 4, 2), 10)
This question already has answers here:
How to find the difference in value in every two consecutive rows in R?
(4 answers)
Closed 7 years ago.
I have a dataframe like so:
df <- data.frame(start=c(5,4,2),end=c(2,6,3))
start end
5 2
4 6
2 3
And I want the following result:
start end diff
5 2
4 6 1
2 3 -1
Essentially it is:
end[2] (second row) - start[1] = 6-5=1
and end[3] - start[2] = 3-4 = -1
What is a good way of doing this in R?
Just a simple vector subtraction should work
df$diff <- c(NA,df[2:nrow(df), 2] - df[1:(nrow(df)-1), 1])
start end diff
1 5 2 NA
2 4 6 1
3 2 3 -1
library(data.table)
setDT(df)[,value:=end-shift(start,1,type="lag")]
start end value
1: 5 2 NA
2: 4 6 1
3: 2 3 -1