#normalization

list_sl=[]
list_sw=[]
list_pl=[]
list_pw=[]
for sl in ds['sepal length']:
    sl = (sl-min(ds['sepal length']))/(max(ds['sepal length'])-min(ds['sepal length']))
    list_sl.append(sl)
for sw in ds['sepal width']:
    sw = (sw-min(ds['sepal width']))/(max(ds['sepal width'])-min(ds['sepal width']))
    list_sw.append(sw)    
for pl in ds['petal length']:
    pl = (pl-min(ds['petal length']))/(max(ds['petal length'])-min(ds['petal length']))
    list_pl.append(pl)
for pw in ds['petal width']:
    pw = (pw-min(ds['petal width']))/(max(ds['petal width'])-min(ds['petal width']))
    list_pw.append(pw) 

X = np.array( list(zip(list_sl,list_sw, list_pl, list_pw)) )