# quantile!

quantile!(v, p)

Like `quantile`, but overwrites the input vector.

## Examples

1. Calculate the median of a vector:

``````julia> v = [1, 4, 3, 7, 2, 9];
julia> quantile!(v, 0.5)
6-element Array{Int64,1}:
1
2
3
4
7
9``````

This example calculates the median of the vector `v` using the `quantile!` function.

2. Determine quartiles of a dataset:

``````julia> data = [12, 45, 67, 23, 9, 34, 56, 78, 90, 1];
julia> quantile!(data, [0.25, 0.5, 0.75])
10-element Array{Int64,1}:
12
34
56
23
9
12
45
67
78
90``````

Here, the `quantile!` function is used to calculate the quartiles (25th, 50th, and 75th percentiles) of the `data` vector.

3. Calculate deciles of a dataset:
``````julia> numbers = [5, 10, 15, 20, 25, 30, 35, 40, 45, 50];
julia> quantile!(numbers, [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9])
10-element Array{Int64,1}:
5
10
15
20
25
30
35
40
45
50``````

This example demonstrates how to calculate deciles (10th, 20th, 30th, ..., 90th percentiles) of the `numbers` vector using `quantile!`.

Common mistake example:

``````julia> arr = [5, 10, 15, 20];
julia> quantile!(arr, 1.5)
ERROR: ArgumentError: `p` must be a scalar or a vector of percentiles in the range [0,1].``````

In this example, the `p` argument provided is out of range. The `p` argument should be a scalar or a vector of percentiles between 0 and 1. Make sure to pass valid values to the `quantile!` function to avoid such errors.