ValueError: x and y must be the same size

Question

import numpy as np
import pandas as pd
import matplotlib.pyplot as pt

data1 = pd.read_csv(\'stage1_labels.csv\')

X = data1.iloc[:, :-1].values
y = data1.iloc[:, 1]         


        

Answer 1

Slicing with [:, :-1] will give you a 2-dimensional array (including all rows and all columns excluding the last column).

Slicing with [:, 1] will give you a 1-dimensional array (including all rows from the second column). To make this array also 2-dimensional use [:, 1:2] or [:, 1].reshape(-1, 1) or [:, 1][:, None] instead of [:, 1]. This will make x and y comparable.

---

An alternative to making both arrays 2-dimensional is making them both one dimensional. For this one would do [:, 0] (instead of [:, :1]) for selecting the first column and [:, 1] for selecting the second column.