Arrays in Julia are mutable data type collections. Unlike other languages, Julia does not require users to explicitly define the type of an array before assigning elements to it. Instead, Julia automatically selects the correct data type and decides the data type of the elements stored in it.
Arrays in Julia are divided into rows and columns. This is done using square brackets around the array elements. There are two types of arrays in Julia: a row-based array, which is also called a matrix, and a multi-dimensional array, also called a vector. The row-based array is the most straightforward type of array in Julia.
It can hold elements of any data type. This makes it convenient for performing operations on values based on index. There are several operations available in Julia for modifying the values of arrays. Some of these operations support parallel operation when multiple threads are used. If the operation supports multi-threading, Julia will spawn separate tasks for each transformation. If a transformation involves a lock, Julia will not be able to perform the operation in parallel. However, this is not necessarily a problem, as Julia has a parallel processing system.
Some operations support multi-threading when enough rows are available. However, the exact threshold is not defined. When the operation is performed on a large DataFrame, it may be worthwhile to perform the operation row by row. For example, adding a column to a DataFrame will not be much faster than adding an element at a particular index.
It is also possible to delete specific elements of an array in Julia. However, this is not possible with 2D arrays. For example, if you wanted to delete an element from the first row of a two-dimensional array, you would need to create a new array with the same number of elements and then delete the element. To do this, you could use the deleteat! function, which deletes an element from a specific index. This is not a very common operation in Julia, but is useful if you need to remove a specific element.
One other option is to delete the entire column. However, this is not a very common operation in Julia, as it requires the user to create a new array with the same amount of elements. The user could merge the new data frame later.
Another operation is the printx function. This function does the same thing as the println function, but it returns nothing. It also allows users to create a data frame with all the columns of a particular type. However, if the user has selected all columns of a particular type, this function is not necessary.
There are several other operations that can be applied to arrays, such as reshape and push! These operations can be useful for adding new elements to the array, which resizes the array. For example, reshape can be used to reshape the size of a 1D array into a 2D array, or to resize a 2D array into a 3D array.