问题描述
我正在尝试使用pandas从DataFrame中的所有元素中减去一个数字。但是,仅减去第一个元素,其他元素得到NaN
。
以下是数据: DataFrame_3x5.csv
A B C
0.1 0.3 0.5
0.2 0.4 0.6
0.3 0.5 0.7
0.4 0.6 0.8
0.5 0.7 0.9
这是我的代码:
import pandas as pd
data = pd.read_csv(r"DataFrame_3x5.csv")
df = pd.DataFrame(data)
medianList = pd.DataFrame()
for i in range(0,data.shape[1]):
medianList = medianList.append([df.iloc[:,i].median()],ignore_index=True)
for i in range(0,data.shape[1]):
print(data.iloc[:,i])
print(medianList.iloc[i])
print(data.iloc[:,i] - medianList.iloc[i])
# print(data.iloc[:,i].sub([medianList.iloc[i]],axis='columns')) # doesn't work
结果如下:
0 0.1
1 0.2
2 0.3
3 0.4
4 0.5
Name: A,dtype: float64
0 0.3
Name: 0,dtype: float64
0 -0.2
1 NaN
2 NaN
3 NaN
4 NaN
dtype: float64
0 0.3
1 0.4
2 0.5
3 0.6
4 0.7
Name: B,dtype: float64
0 0.5
Name: 1,dtype: float64
0 -0.2
1 NaN
2 NaN
3 NaN
4 NaN
dtype: float64
0 0.5
1 0.6
2 0.7
3 0.8
4 0.9
Name: C,dtype: float64
0 0.7
Name: 2,dtype: float64
0 -0.2
1 NaN
2 NaN
3 NaN
4 NaN
dtype: float64
我的期望:
0 -0.2
1 -0.1
2 0.0
3 0.1
4 0.2
根据this site,
print(data.iloc[:,axis='columns'))
...应该可以,但实际上会产生错误:
ValueError: No axis named columns for object type <class 'pandas.core.series.Series'>
我不知道该怎么办。请帮我。谢谢。
解决方法
您可以这样做:
df - df.median(axis=0)
和熊猫会照顾用来计算值的轴
,一个简单的解决方案:
$rating->user->first()->firstName
,
我认为,如果您先尝试dropna
,然后简单地减去它就可以了
df=df.dropna(how='any')
df['Sub']=int(df['A']) - int(df['B']) - int(df['C'])
,
import pandas as pd
data = pd.read_csv(r"DataFrame_3x5.csv")
df = pd.DataFrame(data)
medianList = pd.DataFrame()
for i in range(0,data.shape[1]):
medianList = medianList.append([df.iloc[:,i].median()],ignore_index=True)
df1 = pd.DataFrame(columns=['A'])
j=0
for i in range(0,data.shape[0]):
print(data['A'].iloc[i]) # one column
print(medianList.iloc[i]) #1 value
print(data['A'].iloc[i] - medianList.iloc[j])