After I change your, arff file it works:
NB: I removed the single code from the second column of the attribute.
Here is the arff file:
@relation cleveland-14-heart-disease
@attribute age real
@attribute sex { female, male}
@attribute cp { typ_angina, asympt, non_anginal, atyp_angina}
@attribute trestbps real
@attribute chol real
@attribute fbs { t, f}
@attribute restecg { left_vent_hyper, normal, st_t_wave_abnormality}
@attribute thalach real
@attribute exang { no, yes}
@attribute oldpeak real
@attribute slope { up, flat, down}
@attribute ca real
@attribute thal { fixed_defect, normal, reversable_defect}
@attribute class { negative, positive}
@data
63,male,typ_angina,145,233,t,left_vent_hyper,150,no,2.3,down,0,fixed_defect,negative
37,male,non_anginal,130,250,f,normal,187,no,3.5,down,0,normal,negative
41,female,atyp_angina,130,204,f,left_vent_hyper,172,no,1.4,up,0,normal,negative
56,male,atyp_angina,120,236,f,normal,178,no,0.8,up,0,normal,negative
57,female,asympt,120,354,f,normal,163,yes,0.6,up,0,normal,negative
57,male,asympt,140,192,f,normal,148,no,0.4,flat,0,fixed_defect,negative
Snippet and output:
:/tmp:~ cat a.py
import arff
for row in arff.load('heart_train.arff'):
print(row.sex)
:/tmp:~ python a.py
male
male
female
male
female
male
:/tmp:~
male
:/tmp:~