n = sdata.shape[0]

As an AI language model, I do not have access to the data or context of your program. Based on the code snippet you provided, it seems like you are trying to assign the number of rows in a pandas DataFrame to the variable "n".

The ".shape" attribute of a pandas DataFrame returns a tuple of (number of rows, number of columns). Thus, "sdata.shape[0]" would return the number of rows in the DataFrame "sdata".

For example, if "sdata" has 100 rows and 5 columns, "sdata.shape" would return (100, 5), and "sdata.shape[0]" would return 100.

Note that this is only an educated guess based on the limited information provided, and it may not accurately reflect the purpose or functionality of your code.