# Iteration
## Definition
Execute multiple steps on an array until all results are output.
The iteration step performs the same steps on each item in a list. To use iteration, ensure that the input value is formatted as a list object. The iteration node allows AI workflows to handle more complex processing logic. It is a user-friendly version of the loop node, making some compromises in customization to allow non-technical users to quickly get started.
## Scenarios
### **Example 1: Long Article Iteration Generator**
1. Enter the story title and outline in the **Start Node**.
2. Use a **Generate Subtitles and Outlines Node** to use LLM to generate the complete content from user input.
3. Use a **Extract Subtitles and Outlines Node** to convert the complete content into an array format.
4. Use an **Iteration Node** to wrap an **LLM Node** and generate content for each chapter through multiple iterations.
5. Add a **Direct Answer Node** inside the iteration node to achieve streaming output after each iteration.
**Detailed Configuration Steps**
1. Configure the story title (title) and outline (outline) in the **Start Node**.
2. Use a **Generate Subtitles and Outlines Node** to convert the story title and outline into complete text.
3. Use a **Extract Subtitles and Outlines Node** to convert the story text into an array (Array) structure. The parameter to extract is `sections`, and the parameter type is `Array[Object]`.
{% hint style="info" %}
The effectiveness of parameter extraction is influenced by the model's inference capability and the instructions given. Using a model with stronger inference capabilities and adding examples in the **instructions** can improve the parameter extraction results.
{% endhint %}
4. Use the array-formatted story outline as the input for the iteration node and process it within the iteration node using an **LLM Node**.
Configure the input variables `GenerateOverallOutline/output` and `Iteration/item` in the LLM Node.
{% hint style="info" %}
Built-in variables for iteration: `items[object]` and `index[number]`.
`items[object]` represents the input item for each iteration;
`index[number]` represents the current iteration round;
{% endhint %}
1. Configure a **Direct Reply Node** inside the iteration node to achieve streaming output after each iteration.
2. Complete debugging and preview.
### **Example 2: Long Article Iteration Generator (Another Arrangement)**
* Enter the story title and outline in the **Start Node**.
* Use an **LLM Node** to generate subheadings and corresponding content for the article.
* Use a **Code Node** to convert the complete content into an array format.
* Use an **Iteration Node** to wrap an **LLM Node** and generate content for each chapter through multiple iterations.
* Use a **Template Conversion** Node to convert the string array output from the iteration node back to a string.
* Finally, add a **Direct Reply Node** to directly output the converted string.
## What is Array Content
A list is a specific data type where elements are separated by commas and enclosed in `[` and `]`. For example:
**Numeric:**
```
[0,1,2,3,4,5]
```
**String:**
```
["Monday", "Tuesday", "Wednesday", "Thursday"]
```
**JSON Object:**
```
[
{
"name": "Alice",
"age": 30,
"email": "alice@example.com"
},
{
"name": "Bob",
"age": 25,
"email": "bob@example.com"
},
{
"name": "Charlie",
"age": 35,
"email": "charlie@example.com"
}
]
```
## Nodes Supporting Array Return
* Code Node
* Parameter Extraction
* Knowledge Base Retrieval
* Iteration
* Tools
* HTTP Request
## How to Obtain Array-Formatted Content
* Return Using the CODE Node
* Return Using the Parameter Extraction Node
## How to Convert an Array to Text
The output variable of the iteration node is in array format and cannot be directly output. You can use a simple step to convert the array back to text.
* **Convert Using a Code Node**
Code Example:
```
def main(articleSections: list):
data = articleSections
return {
"result": "/n".join(data)
}
```
* **Convert Using a Template Node**
Code Example:
```
{{ articleSections | join("/n") }}
```
---
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