I have been following this Python linear regression tutorial: https://medium.com/@contactsunny/linear-regression-in-python-using-scikit-learn-f0f7b125a204
Using the following dataset: https://github.com/contactsunny/data-science-examples/blob/master/salaryData.csv
My problem is with the following piece of code:
x = dataset.iloc[:, :-1].values
What does the negation(-1) do here? Why do I get an error If I use the following as an alternate:
x = dataset.iloc[:, 0].values
It means, get all columns except the last column:
df = pd.DataFrame(np.random.randint(0,100,(5,5)), index=[*'abcde'], columns=[*'ABCDE'])
df.iloc[:,:-1]
Output:
A B C D
a 79 23 9 89
b 67 60 32 82
c 66 18 41 67
d 90 51 63 29
e 34 65 82 82
This statement gets all rows and slices the columns to filter out the last. And, there is no error by your second statement it is good statement.
df.iloc[:, 0]
Output:
a 79
b 67
c 66
d 90
e 34
Name: A, dtype: int3
Get all rows of the first column (position 0).