Repository: evidentlyai/evidently
Issue: data missing in the report
Root cause: Documentation Deficiency

Hi 

I was trying to generate a classification dashboard. The "reference" dataframe has 128770 rows, however, the dashboard only shows that it has 122 rows (number of objects). And for "current" dataframe, it has 632337 rows, but the dashboard only shows it has 1079 rows. I am not sure what went wrong. 

Yang

Hi @superyang713 

Looks very interesting. My current guess is that it can be related to the ```nan``` values.
Could you please check the amount of the rows which have a least one ```nan``` value in? I assume that the amount of skipped rows will be equal to the amount of the rows with nans, but lets check first.

The following commands can be handy:
```
#column-based nans statistics
data.isna().sum(axis=0)

#row-based nans statistics
data.isna().sum(axis=1)

#total amount of the rows with nans
raw_data.isna().sum(axis=1).sum()
```

Thank you for the reply. You are right, the dataset has missing values.  Sorry I just started using the package, and did not know that I have to fill out the missing values before generating the dashboard.

My trained model is actually a sklearn pipeline that has an imputer  and other transformers in it.  So I only need to feed the raw data into the model. But for generating the Dashboard, I have to use fill out the missing values first then. Thank you for the response. 

Hi @superyang713 ,

No worries it all! I wanted to thank you for bringing this up! To be honest, it is not exactly how we plan to handle missing values (currently all the rows with the missing values are just ignored). We are going to offer some more ```nan``` handling strategies there.

 Hi All,
I'm using evidently as API and I sent my data to this API, and it gives me HTML report in response. Whatever report I'm getting, it is empty. I have ensured to drop NAN values, but still the report is empty. I am confused why it is giving empty report. Can anyone please help this out. Attached is the screenshot of the empty report.
Thanks
![evidently_empty_report](https://user-images.githubusercontent.com/36502726/136516323-0de6846a-0f50-4581-bb9a-8047872ead2e.png)


Hi @zawster!
 
Unfortunately, we could not reproduce the bug on our side.

One only idea we have is that something similar does happen if the column_mapping is mixed up: for example, if the names of the features listed as numerical and categorical in the column_mapping do not match the actual column names. 

Could you verify if the column_mapping is implemented correctly?

If that is not too confidential, we can check it on our side if you share with us the column_mapping configuration and the preview of the table (e.g. first couple of rows of a table with the column names). You can join our Discord and send it in a private message: https://discord.gg/xZjKRaNp8b

If that is not the case, could you share a bit more information? Does it happen for you only with a particular dataset? 

Hi @zawster 

We changed the data processing strategy in one of the latest releases. Namely, we added the step of copying the dataframe. All operations are now performed on the copy - this could have a positive effect on this problem.

In any case, if the dashboard still does not work correctly, please reopen the issue or come to talk to our Discord https://discord.gg/xZjKRaNp8b. We will be needed some more tech details in this case (evidently version, your environment, what kind of data you work with)  and do our best to solve this.

Okay thanks @emeli-dral I will check with new release and validate it. Thanks for the response.