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I have the following line of code:
X = data.iloc[:, :-1].values
I can’t understand why : before the -1.
1 answer
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When you leave the two points blank, it means you want all the indexes to return.
The first ":" means that it will read from the first to the last line (index).
The "," means the next ":" deals with the columns.
":-1" means that it returns from the first column to the "-1" column, which corresponds to the last column.
Thus, it returns all rows and columns of the dataframe.
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It means you’re reading backwards from the list, overall I think the code is doing is reversing the positions, what was X1 is assigned with YN and XN, with Y1
– FourZeroFive
just giving more details the ":" means will pick up from "index x até index y", example 1:3, pick from index 1 to 3, in your case it will catch up to the penultimate column
– Lucas Miranda