---
title: "Numeric Variables"
description: "Learn how to incorporate external numeric variables to improve your forecasting accuracy."
icon: "binary"
---

## What Are Exogenous Variables?

Exogenous variables or external factors are crucial in time series forecasting 
as they provide additional information that might influence the prediction. 
These variables could include holiday markers, marketing spending, weather data, 
or any other external data that correlate with the time series data you are 
forecasting.

For example, if you're forecasting ice cream sales, temperature data could serve 
as a useful exogenous variable. On hotter days, ice cream sales may increase.


## How to Use Exogenous Variables


[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/Nixtla/nixtla/blob/main/nbs/docs/tutorials/01_exogenous_variables_reworked.ipynb)

To incorporate exogenous variables in TimeGPT, you'll need to pair each point
in your time series data with the corresponding external data.

### Step 1: Import Packages

Import the required libraries and initialize the Nixtla client.


```python
import pandas as pd
from nixtla import NixtlaClient

nixtla_client = NixtlaClient(
    # defaults to os.environ.get("NIXTLA_API_KEY")
    api_key="my_api_key_provided_by_nixtla"
)
```

### Step 2: Load Dataset

In this tutorial, we'll predict day-ahead electricity prices. The dataset contains:

- Hourly electricity prices (`y`) from various markets (identified by `unique_id`)
- Exogenous variables (`Exogenous1` to `day_6`)

```python
df = pd.read_csv("https://raw.githubusercontent.com/Nixtla/transfer-learning-time-series/main/datasets/electricity-short-with-ex-vars.csv")
df.head()
```

| unique_id   | ds                    | y       | Exogenous1   | Exogenous2   | day_0   | day_1   | day_2   | day_3   | day_4   | day_5   | day_6   |
| ----------- | --------------------- | ------- | ------------ | ------------ | ------- | ------- | ------- | ------- | ------- | ------- | ------- |
| BE          | 2016-10-22 00:00:00   | 70.00   | 57253.0      | 49593.0      | 0.0     | 0.0     | 0.0     | 0.0     | 0.0     | 1.0     | 0.0     |
| BE          | 2016-10-22 01:00:00   | 37.10   | 51887.0      | 46073.0      | 0.0     | 0.0     | 0.0     | 0.0     | 0.0     | 1.0     | 0.0     |
| BE          | 2016-10-22 02:00:00   | 37.10   | 51896.0      | 44927.0      | 0.0     | 0.0     | 0.0     | 0.0     | 0.0     | 1.0     | 0.0     |
| BE          | 2016-10-22 03:00:00   | 44.75   | 48428.0      | 44483.0      | 0.0     | 0.0     | 0.0     | 0.0     | 0.0     | 1.0     | 0.0     |
| BE          | 2016-10-22 04:00:00   | 37.10   | 46721.0      | 44338.0      | 0.0     | 0.0     | 0.0     | 0.0     | 0.0     | 1.0     | 0.0     |


### Step 3: Forecast without Exogenous Variables

First, let's create a baseline forecast without using any exogenous variables.

```python
timegpt_fcst_no_ex_vars = nixtla_client.forecast(
    df=df[["unique_id", "ds", "y"]],
    h=24,
    level=[80, 90]
)
```

### Step 4: Forecasting with Exogenous Variables

Next, let's create a forecast using the exogenous variables. To make a forecast 
using exogenous variables, you need to provide historical and future exogenous 
values. Below is an example dataset containing future exogenous variables. Note 
that it only contains the future exogenous variable values not the target 
variable `y`. We need to forecast this target variable using the exogenous 
variables provided.

```python
future_ex_vars_df = pd.read_csv("https://raw.githubusercontent.com/Nixtla/transfer-learning-time-series/main/datasets/electricity-short-future-ex-vars.csv")
future_ex_vars_df.head()
```

| unique_id | ds                   | Exogenous1 | Exogenous2 | day_0 | day_1 | day_2 | day_3 | day_4 | day_5 | day_6 |
|-----------|----------------------|------------|------------|-------|-------|-------|-------|-------|-------|-------|
| BE        | 2016-12-31 00:00:00  | 70318.0    | 64108.0    | 0.0   | 0.0   | 0.0   | 0.0   | 0.0   | 1.0   | 0.0   |
| BE        | 2016-12-31 01:00:00  | 67898.0    | 62492.0    | 0.0   | 0.0   | 0.0   | 0.0   | 0.0   | 1.0   | 0.0   |
| BE        | 2016-12-31 02:00:00  | 68379.0    | 61571.0    | 0.0   | 0.0   | 0.0   | 0.0   | 0.0   | 1.0   | 0.0   |
| BE        | 2016-12-31 03:00:00  | 64972.0    | 60381.0    | 0.0   | 0.0   | 0.0   | 0.0   | 0.0   | 1.0   | 0.0   |
| BE        | 2016-12-31 04:00:00  | 62900.0    | 60298.0    | 0.0   | 0.0   | 0.0   | 0.0   | 0.0   | 1.0   | 0.0   |

Ensure you maintain consistent data formatting and columns in both historical 
and future exogenous datasets (e.g., dates, unique_id, variable names).

```python
timegpt_fcst_ex_vars = nixtla_client.forecast(
    df=df,
    X_df=future_ex_vars_df,
    h=24,
    level=[80, 90]
)
```

### Step 5: Forecast Visualization

Once you have generated your forecasts, you can visualize the results to compare 
forecasts between the two methods above.

```python
timegpt_fcst_no_ex_vars.rename(columns={"TimeGPT": "TimeGPT_no_ex_vars"}, inplace=True)
timegpt_fcst_ex_vars.rename(columns={"TimeGPT": "TimeGPT_ex_vars"}, inplace=True)

all_forecasts = (
    timegpt_fcst_no_ex_vars
    .merge(
        timegpt_fcst_ex_vars,
        how='outer',
        on=["unique_id", "ds"]
    )
)
```

```python
nixtla_client.plot(
    df[["unique_id", "ds", "y"]],
    all_forecasts,
    max_insample_length=1000,
)
```

<Frame>
  ![Forecast chart](/images/docs/exo_no_exo_comparison.png)
</Frame>

## Key Takeaways

- Exogenous variables enrich time series forecasting.
- Ensure proper alignment of historical and future exogenous data.

## Next Steps

  Congratulations! You have mastered the fundamentals of adding exogenous 
  variables to your TimeGPT forecasts. Keep refining your approach by 
  
- Exploring feature engineering to create domain-specific exogenous data.
- Experimenting with different modeling approaches for external variables.
- Validating forecast accuracy by comparing with real future data.