# concatenate-columns

## Description

<mark style="color:purple;">`concatenate-columns`</mark> *adaptor concatenates values from two or more columns into a single value, with or without a delimiter between them.*

The order given in the `columns` input is the order in which the values are concatenated. By default, the values will be concatenated without a delimiter between them, this can be changed by setting the separator value.

## Inputs

**`data`**\
Type: `datatable`\
Required: Yes\
The datatable containing the columns to be concatenated.

**`columns`**\
Type: `list`\
Required: Yes\
A list of columns to be concatenated. The output value matches the listed order.

**`separator`**\
Type: `text`\
Required: No\
Specifies text to separate each concatenated value. Defaults to `""` (blank).

**`concatenated column`**\
Type: `text`\
Required: Yes\
The new column containing concatenated values.

## Outputs

**`data`**\
Type: `datatable`\
A datatable with the concatenated column added.

## Examples

### Example 1: Default behaviour.

#### Inputs:

`data`:

| Sample ID | A | B | C |
| --------- | - | - | - |
| Sample A  | R | R | R |
| Sample B  | S | R | S |
| Sample C  | R | S | I |
| Sample D  | I | R | R |
| Sample E  | R | r | R |
| Sample F  | r | r | r |

`columns`:

* A
* B
* C

`concatenated column`: Result

#### Outputs:

`data`:

| Sample ID | A | B | C | Result |
| --------- | - | - | - | ------ |
| Sample A  | R | R | R | RRR    |
| Sample B  | S | R | S | SRS    |
| Sample C  | R | S | I | RSI    |
| Sample D  | I | R | R | IRR    |
| Sample E  | R | r | R | RrR    |
| Sample F  | r | r | r | rrr    |

-> Concatenated the columns `A`, `B` and `C` and added the value to the `Result` column.

### Example 2: Concatenation with a separator.

#### Inputs:

`data`:

| Sample ID | A | B | C |
| --------- | - | - | - |
| Sample A  | R | R | R |
| Sample B  | S | R | S |
| Sample C  | R | S | I |
| Sample D  | I | R | R |
| Sample E  | R | r | R |
| Sample F  | r | r | r |

`columns`:

* A
* B
* C

`concatenated column`: Result

`separator`: ;

#### Outputs:

`data`:

| Sample ID | A | B | C | Result |
| --------- | - | - | - | ------ |
| Sample A  | R | R | R | R;R;R  |
| Sample B  | S | R | S | S;R;S  |
| Sample C  | R | S | I | R;S;I  |
| Sample D  | I | R | R | I;R;R  |
| Sample E  | R | r | R | R;r;R  |
| Sample F  | r | r | r | r;r;r  |

-> Concatenated the columns `A`, `B` and `C` and added the value to the `Result` column with a `;` separator.

## Use Cases

* Use this adaptor to generate a composite key or ID by concatenating multiple column values
* Combining values from different categorical columns can result in a new categorical variable. This can be useful when you want to create a combined label that captures the essence of the data more effectively.
* Concatenating year, month, and day values from separate columns into a new date column
* When working with data that includes components of URLs or file paths, concatenation can be used to construct these addresses in a new column. This is particularly useful when you need to reference external resources or link to specific locations.
* Concatenating values allows for the creation of a new column with a specific format suitable for display or visualisation labeling purposes.


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