The Complete Rust Programming Reference Guide

Remove

Vec<T> and VecDeque<T> both remain efficient when removing items. Although, they don't change the amount of memory allocated to the data structure, both types provide a function called shrink_to_fit() to readjust the capacity to the length it has.

On remove, Vec<T> shifts the remaining elements toward the start of the sequence. Like the insert() function, it simply copies the entire remaining data with an offset, shown as follows:

#[stable(feature = "rust1", since = "1.0.0")]pub fn remove(&mut self, index: usize) -> T {    let len = self.len();    assert!(index < len);    unsafe {        // infallible        let ret;        {            // the place we are taking from.            let ptr = self.as_mut_ptr().add(index);            // copy it out, unsafely having a copy of the value on // the stack ...