Columns and DataType Not Explicitly Set on line 13 of test_ohe.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:

Kaggler/tests/preprocessing/test_ohe.py

Lines 3 to 23 in 510e70b

	import pandas as pd
	from kaggler.preprocessing import OneHotEncoder
	N_OBS = int(1e6)
	N_FEATURE = 10
	N_CATEGORY = 1000
	def test():
	df = pd.DataFrame(
	np.random.randint(0, N_CATEGORY, size=(N_OBS, N_FEATURE)),
	columns=["c{}".format(x) for x in range(N_FEATURE)],
	)
	profiler = cProfile.Profile(subcalls=True, builtins=True, timeunit=0.001)
	ohe = OneHotEncoder(min_obs=100)
	profiler.enable()
	ohe.fit(df)
	X_new = ohe.transform(df)
	profiler.disable()
	profiler.print_stats()

.

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

File: https://github.com/jeongyoonlee/Kaggler/blob/master/kaggler/metrics/plot.py#L84-L94 Line: 89
File: https://github.com/jeongyoonlee/Kaggler/blob/master/kaggler/metrics/plot.py#L87-L97 Line: 92
File: https://github.com/jeongyoonlee/Kaggler/blob/master/kaggler/metrics/plot.py#L98-L108 Line: 103
File: https://github.com/jeongyoonlee/Kaggler/blob/master/kaggler/model/automl.py#L205-L215 Line: 210
File: https://github.com/jeongyoonlee/Kaggler/blob/master/kaggler/preprocessing/categorical.py#L303-L313 Line: 308
.

I hope this information is helpful!