如何从浮点数中取前一位或两位数? [英] How to take first one or two digits from float number?

问题描述

我有一个Pandas数据框.在一个系列中，我将小时和分钟的时间表示为float，如下所示.我只想要几个小时:

I have a Pandas dataframe. In a series, I have time in hour and minute represented as float, as below. I want only the hours:

时间列值从(1到12)的示例:

1000.0 -> 10
901.0 ->  9

时间列值从(13到24)的示例:

1850.0 -> 18
2301.0 -> 23

我已经尝试过这段代码，但是直到关闭编辑器才花费很长时间，所以我看不到结果

I have tried this code but it takes very long time until I close the editor so I didn't see the result

for index,row in df.iterrows():
    if(row['time']<=959.0):
        row['hour']= int(str(row['dep_time'])[:1])
    elif row['dep_time']>959.0: 
         row['dep_hour']=int(str(row['dep_time'])[:2])

推荐答案

对于Pandas，在向量化方法可用时不要迭代行.在这种情况下，您可以使用下限分割，后跟 pd.Series.astype :

With Pandas, don't iterate rows when vectorised methods are available. In this case, you can use floor division followed by pd.Series.astype:

df['hour'] = (df['dep_time'] // 100).astype(int)

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