Columns and DataType Not Explicitly Set on line 61 of data.py

[CodeSmileBot]

Hello!

I found an AI-Specific Code smell in your project.
The smell is called: Columns and DataType Not Explicitly Set

You can find more information about it in this paper: https://dl.acm.org/doi/abs/10.1145/3522664.3528620.

According to the paper, the smell is described as follows:

Problem	If the columns are not selected explicitly, it is not easy for developers to know what to expect in the downstream data schema. If the datatype is not set explicitly, it may silently continue the next step even though the input is unexpected, which may cause errors later. The same applies to other data importing scenarios.
Solution	It is recommended to set the columns and DataType explicitly in data processing.
Impact	Readability

Example:

### Pandas Column Selection
import pandas as pd
df = pd.read_csv('data.csv')
+ df = df[['col1', 'col2', 'col3']]

### Pandas Set DataType
import pandas as pd
- df = pd.read_csv('data.csv')
+ df = pd.read_csv('data.csv', dtype={'col1': 'str', 'col2': 'int', 'col3': 'float'})

You can find the code related to this smell in this link:

alibi/alibi/utils/data.py

Lines 51 to 71 in e458ab3

	if data.ndim != 2:
	raise TypeError('Expected a 2-dimensional dataframe or array')
	n_features = data.shape[1]
	if isinstance(data, np.ndarray):
	# if numpy array, we need categorical_columns, otherwise impossible to infer
	if categorical_columns is None:
	raise ValueError('If passing a numpy array, `categorical_columns` is required')
	elif not all(isinstance(ix, int) for ix in categorical_columns):
	raise ValueError('If passing a numpy array, `categorical_columns` must be a list of integers')
	data = pd.DataFrame(data)
	# infer categorical columns
	if categorical_columns is None:
	try:
	categorical_columns = [i for i in range(n_features) if data.iloc[:, i].dtype == 'O'] # NB: 'O'
	except AttributeError:
	raise
	# create the map
	category_map = {}

.

I also found instances of this smell in other files, such as:

File: https://github.com/SeldonIO/alibi/blob/master/alibi/datasets/default.py#L249-L259 Line: 254
File: https://github.com/SeldonIO/alibi/blob/master/alibi/explainers/ale.py#L519-L529 Line: 524
File: https://github.com/SeldonIO/alibi/blob/master/alibi/explainers/backends/cfrl_tabular.py#L869-L879 Line: 874
.

I hope this information is helpful!