# A to Z of Excel Functions: The MAKEARRAY Function

13 December 2021

*Welcome back to our regular A to Z of Excel Functions blog. Today we look at the MAKEARRAY function. *

**The MAKEARRAY function**

**MAKEARRAY **returns a calculated array of a specified row and column size, by applying a **LAMBDA **function. This function is useful for situations where you wish to combine or transform arrays, as well as being useful for generating data. The syntax is as follows:

**MAKEARRAY(rows, columns, lambda)**

It has the following arguments:

**rows:**this argument is required and represents the number of rows in the array (which must be greater than zero)**columns:**this argument is also required and represents the number of columns in the array (which again must be greater than zero)**lambda:**also necessary, this is the**LAMBDA**that is called to create the array. In particular, this lambda function must take two parameters, namely:**row_index:**the index of the row (row number)**column_index:**the index of the column (column number).

As an example, consider the following:

Imagine, for reasons best known to myself, I wanted to generate an array of colours of the rainbow (albeit with the final colour, ahem, slightly amended). In the image above, I have specified the number of rows (cell **D2**) and the number of columns (cell **D3**) in my array, and listed the colours in cells **B6:B12** inclusive.

The formula in cell **E6** is given by

**=MAKEARRAY(D2, D3, LAMBDA(row, column, INDEX(B6:B12, RANDBETWEEN(1, 7))))**

The first two arguments in this formula are **D2 **and **D3**, which refer to the number of rows and columns for the array to be generated respectively. The final argument of **MAKEARRAY** is the **LAMBDA**, which must take two parameters, corresponding to the value generated by **LAMBDA**, namely:

**row:**the index of the row**column:**the index of the column.

The calculation thus uses the non-dynamic array function **RANDBETWEEN** to generate an integer between one [1] and seven [7] to select from the list of colours of the rainbow, stipulated in cells **B6:B12**. For example, if Excel generates the number 5, the value “Blue” will be chosen, *etc*.

Now it is true that existing functions could be used to achieve the same result, *e.g. *

**=INDEX(B6:B12, RANDARRAY(D2, D3, 1, 7, TRUE))**

This formula seems shorter and simpler, and indeed, may be the better option for this above illustration. But that is exactly what this is – a simple example. As more complex arrays need to be created, existing function counterparts may prove difficult, convoluted or impossible to construct – and this is precisely where **MAKEARRAY** and **LAMBDA** come in.

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every other business day.*

*A full page of the function articles can be found* *here. *