When you deploy or demo a machine learning model, you may find that it behaves differently than how you expected (e.g. the model makes an incorrect prediction) when a user tries it with their own data. Capturing these "hard" data points is important because it allows you to make you machine learning model more reliable and robust.
Gradio simplifies the collection of this data by including a FLAG button with every `Interface`. This allows your user or tester to easily send data back to you, whether the model is running locally or has been shared by setting `share=True`.
## The **Flag** button
Underneath the output interfaces, there is a button marked **Flag**. When a user testing your model sees input with interesting output, such as erroneous or unexpected model behaviour, they can flag the input for the interface creator to review.
When you click the flag button above, the directory where the interface was launched will include a new flagged subfolder, with a csv file inside it. This csv file includes all the data that was flagged.
```directory
+-- flagged/
| +-- logs.csv
```
_flagged/logs.csv_
```csv
num1,operation,num2,Output,timestamp
5,add,7,12,2022-01-31 11:40:51.093412
6,subtract,1.5,4.5,2022-01-31 03:25:32.023542
```
If the interface involves file data, such as for Image and Audio components, folders will be created to store those flagged data as well. For example an `image` input to `image` output interface will create the following structure.
```directory
+-- flagged/
| +-- logs.csv
| +-- image/
| | +-- 0.png
| | +-- 1.png
| +-- Output/
| | +-- 0.png
| | +-- 1.png
```
_flagged/logs.csv_
```csv
im,Output timestamp
im/0.png,Output/0.png,2022-02-04 19:49:58.026963
im/1.png,Output/1.png,2022-02-02 10:40:51.093412
```
If you wish for the user to provide a reason for flagging, you can pass a list of strings to the `flagging_options` argument of Interface. Users will have to select one of the strings when flagging, which will be saved as an additional column to the CSV.
If we go back to the calculator example, the following code will create the interface embedded below it.
When users click the flag button, the csv file will now include a column indicating the selected option.
_flagged/logs.csv_
```csv
num1,operation,num2,Output,flag,timestamp
5,add,7,-12,wrong sign,2022-02-04 11:40:51.093412
6,subtract,1.5,3.5,off by one,2022-02-04 11:42:32.062512
```
## Doing more with the data
Suppose you want to take some action on the flagged data, instead of just saving it. Perhaps you want to trigger your model to retrain, or even just share it with others in a cloud dataset. We've made this super easy with the `flagging_callback` parameter.
For example, below we're going to pipe flagged data from our calculator example into a crowd-sourced Hugging Face Dataset.
You can now see all the examples flagged above in this [public HF dataset](https://huggingface.co/datasets/aliabd/crowdsourced-calculator-demo/blob/main/data.csv).
We created the `gr.HuggingFaceDatasetSaver` class, but you can pass your own custom class as long as it inherits from `FLaggingCallback` defined in [this file](https://github.com/gradio-app/gradio/blob/master/gradio/flagging.py). If you create a cool callback, please contribute it to the repo!
## Privacy
Please make sure your users understand when the data they submit is being saved, and what you plan on doing with it. This is especially important when you use `allow_flagging=auto`. We suggest including this info in the description so that it's read before the interface.
