如何解决“不支持的操作数类型-：'str'和'str'”错误

Question

我正在研究 YouTube API 的一些问题，这些问题使我能够估计每个视频的信息方面（喜欢、不喜欢和观看次数）对形成用户意见的影响。

dff=pd.read_csv('VideosPolarity.csv')
print(dff)
print(dff.columns)

nv=len(dff) # video number
gamma=0.3
polarity=dff['polarity']
dislike=dff['dislikeCount']
like=dff['likeCount']
view=dff['viewCount']
viewNb=len(view)
channelId=dff['channelId'].unique()
users=len(channelId)

sumpolarity=polarity.sum(axis = 0, skipna = True)

avpolarity=sumpolarity/users

VOpinion=[]
for k in range(0,nv):
    value=(((like[k]-dislike[k])/viewNb)*round(avpolarity,1))*round(polarity[k],1)
    VOpinion.append(value)

VideoOpinion=gamma*sum(VOpinion)

print('VideoOpinion:',VideoOpinion)

但是我遇到了这个问题

TypeError                                 Traceback (most recent call last)
<ipython-input-14-aadb106341f9> in <module>
 23 VOpinion=[]
 24 for k in range(0,nv):
 ---> 25     value=(((like[k]-dislike[k])/viewNb)*round(avpolarity,1))*round(polarity[k],1)
 26     VOpinion.append(value)
 27 

 TypeError: unsupported operand type(s) for -: 'str' and 'str'

谁能为我提出解决方案？