df 要浮动的对象

Question

我有一个问题我有这个 df :


**<class 'pandas.core.frame.DataFrame'>
RangeIndex: 44640 entries, 0 to 44639
Data columns (total 4 columns):
 #   Column                 Non-Null Count  Dtype 
---  ------                 --------------  ----- 
 0   NOx_Min_[ppm]          44640 non-null  object
 1   NOx_Min_[mg/m3N]       44640 non-null  object
 2   NOx_corr_Min_[mg/m3N]  44640 non-null  object
 3   NOX                    44640 non-null  object
dtypes: object(4)
memory usage: 1.4+ MB
NOx_Min_[ppm]   NOx_Min_[mg/m3N]    NOx_corr_Min_[mg/m3N]   NOX
0   0   0   0   MMC
1   0   0   0   MMC
2   0   0   0   MMC
3   0   0   0   MMC
4   0   0   0   MMC**

我正在尝试将对象转换为数字 gd['NOX']=pd.to_numeric(gd['NOX']) 和然后通过我的神经网络处理它，但它会产生以下错误：


---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
pandas/_libs/lib.pyx in pandas._libs.lib.maybe_convert_numeric()

ValueError: Unable to parse string "MMC"

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
<ipython-input-11-78184c2df2b2> in <module>()
----> 1 gd['NOX']=pd.to_numeric(gd['NOX'])

/usr/local/lib/python3.7/dist-packages/pandas/core/tools/numeric.py in to_numeric(arg, errors, downcast)
    151         try:
    152             values = lib.maybe_convert_numeric(
--> 153                 values, set(), coerce_numeric=coerce_numeric
    154             )
    155         except (ValueError, TypeError):

pandas/_libs/lib.pyx in pandas._libs.lib.maybe_convert_numeric()

ValueError: Unable to parse string "MMC" at position 0

请问我需要你的帮助

Answer 1

你可以试试：

gd['NOX'].apply(pd.to_numeric, args=('coerce',))

Answer 2

“NOX”列包含不可转换为浮点数的字符串（类似于“MMC”的字符串）。但是，其他列可以转换为浮点数，然后在您的神经网络中使用。

Answer 3

数据框中的 'NOX' 列包含无法转换为数值的字符串值。在这种情况下，如果您在无法解析该值的单元格中接受 Nan(null) 值，只需在函数中设置 errors = "coerce"，如下所示。

gd['NOX']=pd.to_numeric(gd['NOX'], errors = "coerce")

如果您需要将这些值解析为某个值，请使用以下内容并根据需要实施逻辑。

def cast_to_float(x):
    try:
      return float(x)
    except ValueError:
      return sum([ ord(i) for i in x]) # add your logic here

gd['NOX'] = gd['NOX'].apply(cast_to_float)

df 要浮动的对象

df Objects to float

python

type-conversion

dataframe

pandas