Pandas将字符串列和NaN(浮点数)转换为整数,保留NaN

Question

我在转换包含字符串格式(类型:str)和NaN(类型:float64)的2位数字的列时遇到问题.我想以这种方式获得一个新列:NaN,其中有NaN和整数,其中有两个数字的字符串格式.举个例子:我想从列YearBirth1获取列Yearbirth2,如下所示:

YearBirth1  #numbers here are formatted as strings: type(YearBirth1[0])=str
        34  # and NaN are floats: type(YearBirth1[2])=float64.
        76
       Nan
        09
       Nan
        91

YearBirth2  #numbers here are formatted as integers: type(YearBirth2[0])=int
        34  #NaN can remain floats as they were. 
        76
       Nan
         9
       Nan
        91

我试过这个:

csv['YearBirth2'] = (csv['YearBirth1']).astype(int)

正如我所料,我得到了这个错误:

ValueError: cannot convert float NaN to integer

所以我尝试了这个:

csv['YearBirth2'] = (csv['YearBirth1']!=NaN).astype(int)

并得到这个错误:

NameError: name 'NaN' is not defined

最后我试过这个:

csv['YearBirth2'] = (csv['YearBirth1']!='NaN').astype(int)

没有错误,但当我检查列YearBirth2时,这是结果:

YearBirth2:
         1
         1
         1
         1
         1
         1

非常糟糕..我认为这个想法是正确的但是有一个问题让Python能够理解我对NaN的意思..或者我尝试的方法可能是错的..

我也使用了pd.to_numeric()方法,但这种方式我获得了浮点数,而不是整数.

有什么帮助？!谢谢大家!

PS:csv是我的DataFrame的名称; 对不起,如果我不太清楚,我正在改进英语!

Answer 1

您可以使用to_numeric,但无法获得int与NaN价值观-它们将被转换成float:看Na型促销活动.

df['YearBirth2'] = pd.to_numeric(df.YearBirth1, errors='coerce')
print (df)
  YearBirth1  YearBirth2
0         34        34.0
1         76        76.0
2        Nan         NaN
3         09         9.0
4        Nan         NaN
5         91        91.0