python - 在循环中转换 Pandas Dataframes 值

Question

想要使用 object 转换数据帧值 n , y ，和?至0 , 1 ，和0

这是df.head() :

df.head()
party   infants water   budget  physician   salvador    religious   satellite   aid missile immigration synfuels    education   superfund   crime   duty_free_exports   eaa_rsa
0   republican  n   y   n   y   y   y   n   n   n   y   ?   y   y   y   n   y
1   republican  n   y   n   y   y   y   n   n   n   n   n   y   y   y   n   ?
2   democrat    ?   y   y   ?   y   y   n   n   n   n   y   n   y   y   n   n
3   democrat    n   y   y   n   ?   y   n   n   n   n   y   n   y   n   n   y
4   democrat    y   y   y   n   y   y   n   n   n   n   y   ?   y   y   y   y

我尝试使用简单的 for循环:

for names in df.columns.values:
    df.names.replace(('n', 'y'), (0, 1), inplace=True)
    df.names.replace('?', 0, inplace=True)

但它返回给我一个AttributeError: 'DataFrame' object has no attribute 'names'

请与我分享任何转换 object 的想法值进入int值。

Answer 1

我认为你可以使用DataFrame.replace没有就地:

df = df.replace(('n','?','y'), (0,0,1))
#alternative
df = df.replace({'n':0,'?':0,'y':1})

<小时/>

print (df)
        party  infants  water  budget  physician  salvador  religious  \
0  republican        0      1       0          1         1          1   
1  republican        0      1       0          1         1          1   
2    democrat        0      1       1          0         1          1   
3    democrat        0      1       1          0         0          1   
4    democrat        1      1       1          0         1          1   

   satellite  aid  missile  immigration  synfuels  education  superfund  \
0          0    0        0            1         0          1          1   
1          0    0        0            0         0          1          1   
2          0    0        0            0         1          0          1   
3          0    0        0            0         1          0          1   
4          0    0        0            0         1          0          1   

   crime  duty_free_exports  eaa_rsa  
0      1                  0        1  
1      1                  0        0  
2      1                  0        0  
3      0                  0        1  
4      1                  1        1  

通常不建议inplace - link :

The pandas core team discourages the use of the inplace parameter, and eventually it will be deprecated (which means "scheduled for removal from the library"). Here's why:

inplace won't work within a method chain.
The use of inplace often doesn't prevent copies from being created, contrary to what the name implies.
Removing the inplace option would reduce the complexity of the pandas codebase.

在您的代码中，names 是列名称，您只想替换此列的值:

df.names.replace

错误意味着没有列names:

AttributeError: 'DataFrame' object has no attribute 'names'