I have a vector of numbers:
numbers <- c(4,23,4,23,5,43,54,56,657,67,67,435,
453,435,324,34,456,56,567,65,34,435)
How can I hav
Here is a way you could do it with dplyr:
library(tidyverse)
numbers <- c(4,23,4,23,5,43,54,56,657,67,67,435,
453,435,324,34,456,56,567,65,34,435)
ord <- seq(1:(length(numbers)))
df <- data.frame(ord,numbers)
df <- df %>%
count(numbers)
numbers n
<dbl> <int>
1 4 2
2 5 1
3 23 2
4 34 2
5 43 1
6 54 1
7 56 2
8 65 1
9 67 2
10 324 1
11 435 3
12 453 1
13 456 1
14 567 1
15 657 1
The most direct way is sum(numbers == x)
.
numbers == x
creates a logical vector which is TRUE at every location that x occurs, and when sum
ing, the logical vector is coerced to numeric which converts TRUE to 1 and FALSE to 0.
However, note that for floating point numbers it's better to use something like: sum(abs(numbers - x) < 1e-6)
.
There is a standard function in R for that
tabulate(numbers)
If you want to count the number of appearances subsequently, you can make use of the sapply
function:
index<-sapply(1:length(numbers),function(x)sum(numbers[1:x]==numbers[x]))
cbind(numbers, index)
Output:
numbers index
[1,] 4 1
[2,] 23 1
[3,] 4 2
[4,] 23 2
[5,] 5 1
[6,] 43 1
[7,] 54 1
[8,] 56 1
[9,] 657 1
[10,] 67 1
[11,] 67 2
[12,] 435 1
[13,] 453 1
[14,] 435 2
[15,] 324 1
[16,] 34 1
[17,] 456 1
[18,] 56 2
[19,] 567 1
[20,] 65 1
[21,] 34 2
[22,] 435 3
This can be done with outer
to get a metrix of equalities followed by rowSums
, with an obvious meaning.
In order to have the counts and numbers
in the same dataset, a data.frame is first created. This step is not needed if you want separate input and output.
df <- data.frame(No = numbers)
df$count <- rowSums(outer(df$No, df$No, FUN = `==`))
I would probably do something like this
length(which(numbers==x))
But really, a better way is
table(numbers)