---
layout: default
title: Train 
parent: Train and Predict APIs
grand_parent: ML Commons API
has_children: true
nav_order: 10
---

# Train 

The train API operation trains a model based on a selected algorithm. Training can occur both synchronously and asynchronously.

#### Example request 

The following examples use the k-means algorithm to train index data.

**Train with k-means synchronously** 

```json
POST /_plugins/_ml/_train/kmeans
{
    "parameters": {
        "centroids": 3,
        "iterations": 10,
        "distance_type": "COSINE"
    },
    "input_query": {
        "_source": ["petal_length_in_cm", "petal_width_in_cm"],
        "size": 10000
    },
    "input_index": [
        "iris_data"
    ]
}
```
{% include copy-curl.html %}

**Train with k-means asynchronously**

```json
POST /_plugins/_ml/_train/kmeans?async=true
{
    "parameters": {
        "centroids": 3,
        "iterations": 10,
        "distance_type": "COSINE"
    },
    "input_query": {
        "_source": ["petal_length_in_cm", "petal_width_in_cm"],
        "size": 10000
    },
    "input_index": [
        "iris_data"
    ]
}
```
{% include copy-curl.html %}

#### Example response

**Synchronous**

For synchronous responses, the API returns the `model_id`, which can be used to get or delete a model.

```json
{
  "model_id" : "lblVmX8BO5w8y8RaYYvN",
  "status" : "COMPLETED"
}
```

**Asynchronous**

For asynchronous responses, the API returns the `task_id`, which can be used to get or delete a task.

```json
{
  "task_id" : "lrlamX8BO5w8y8Ra2otd",
  "status" : "CREATED"
}
```