import nibabel as nib
num=1
for i in range(155)
    img = nib.load('F:/shujuji/train/'+str(num)+'/mask_GTV.nii.gz')
    img_affine  = img.affine
    img = img.get_data()
    img = img//255
    nib.Nifti1Image(img,img_affine).to_filename('F:/shujuji/train/'+str(num)+'/mask_GTV.nii.gz')
    num+=1