how how iloc[:,1:] works ? can any one explain [:,1:] params

Question

What is the meaning of below lines., especially confused about how iloc[:,1:] is working ? and also data[:,:1]

data = np.asarray(train_df_mv_norm.iloc[:,1:])
X, Y = data[:,1:],data[:,:1]

Here train_df_mv_norm is a dataframe --

Answer 1

Definition: pandas iloc

.iloc[] is primarily integer position based (from 0 to length-1 of the axis), but may also be used with a boolean array.

For example:

df.iloc[:3] # slice your object, i.e. first three rows of your dataframe
df.iloc[0:3] # same
df.iloc[0, 1] # index both axis. Select the element from the first row, second column.
df.iloc[:, 0:5] # first five columns of data frame with all rows

So, your dataframe train_df_mv_norm.iloc[:,1:] will select all rows but your first column will be excluded.

Note that:

• df.iloc[:,:1] select all rows and columns from 0 (included) to 1 (excluded).
• df.iloc[:,1:] select all rows and columns, but exclude column 1.

Answer 2

To complete the answer by KeyMaker00, I add that data[:,:1] means:

• The first : - take all rows.
• :1 - equal to 0:1 take columns starting from column 0, up to (excluding) column 1.

So, to sum up, the second expression reads only the first column from data.

As your expression has the form:

<variable_list> = <expression_list>

each expression is substituted under the corresponding variable (X and Y).

Answer 3

Maybe it will complete the answers before. You will know

1. what you get,
2. its shape
3. how to use it with de column name

    df.iloc[:,1:2]        # get column 1 as a DATAFRAME of shape (n, 1) 
    df.iloc[:,1:2].values # get column 1 as an NDARRAY of shape (n, 1)
    df.iloc[:,1].values   # get column 1 as an NDARRAY of shape ( n,) 
    df.iloc[:,1]          # get column 1 as a SERIES of shape (n,) 
    # iloc with the name of a column 
    df.iloc[:, df.columns.get_loc('my_col')] # maybe there is some more 

elegants methods