The m4_sampling function in the hana_ml.visualizers.m4_sampling module uses the M4 algorithm to visualize big data, taking a DataFrame of time series data and a sampling rate as parameters, and returning a sampled DataFrame.
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Here is a Python code template for the `m4_sampling` function from the `hana_ml.visualizers.m4_sampling` module:

```python
# Import necessary module
from hana_ml.visualizers import m4_sampling

# Define your DataFrame
data = ...

# Define the width
width = ...

# Use the m4_sampling function
sampled_data = m4_sampling(data, width)

# The sampled_data is now a DataFrame that you can use for further processing
print(sampled_data)
```

Please replace `...` with your actual data.