Why Pair plot is taking up the target variable into consideration?
maybe because Surv_status is number.
there are two solution:


define variables:

sns.set_style("whitegrid"); sns.pairplot(patients, hue="Surv_status",vars=["AGE", "Op_Year", "axil_nodes_det"], size=3);

change target value to a string:

patients['Surv_status'] = patients['Surv_status'].astype(str)



or 

    patients['Surv_status'] = patients['Surv_status'].str