我有一个函数和一个规则要应用在df上。
def apply_rule(df, rule):
df['legal'] = df.apply(rule)
def greater_than_mean_plus_1_std():
return df['col1']>df['col1'].mean()+df['col1'].std()
apply_rule(df, greater_than_mean_plus_1_std)
我想在df上应用一个规则,它可以生成一个新列,告诉我row的值是否大于mean+std
但是对于df.apply(),我不能在这里使用df.mean()和df.std()。
AttributeError: 'float' object has no attribute 'mean'
有办法吗?或者我必须使用df.apply()以外的方法?
编辑:
print(df.head())
col1
0 7.2
1 7.2
2 7.2
3 7.2
4 7.2
预期输出:
col1 legal
0 7.2 False
1 7.2 False
2 7.2 False
3 7.2 False
4 7.2 False
这里不需要使用apply
df['legal'] = df['col1'] > (df['col1'].mean()+df['col1'].std())
如果你想使用apply
,你可以使用DataFrame。
df['legal'] = df.apply(lambda row: row['col1'] > (df['col1'].mean()+df['col1'].std()), axis=1)
# or
df['legal'] = df['col1'].apply(lambda x: x > (df['col1'].mean()+df['col1'].std()))
您可以使用:
def apply_rule(df, rule):
df['legal'] = rule(df) # <- change here
def greater_than_mean_plus_1_std(df): # <- change here
return df['col1'] > df['col1'].mean() + df['col1'].std()
apply_rule(df, greater_than_mean_plus_1_std)
输出:
# df = pd.DataFrame({'col1': range(10)})
>>> df
col1 legal
0 0 False
1 1 False
2 2 False
3 3 False
4 4 False
5 5 False
6 6 False
7 7 False
8 8 True
9 9 True
先计算平均值和STD值,
col1_mean = df["col1"].mean()
col1_std = df["col1"].std()
然后像这样使用这些预先计算的值
df["legal"] = df["col1"].apply(lamdba x: x > col1_mean + col1_std)
,如果你想让它函数化,你可以使用lambda:
col1_mean = df["col1"].mean()
col1_std = df["col1"].std()
greater_than_mean_plus_1_std = lambda x: x > col1_mean + col1_std
def apply_rule(df, rule, column):
df['legal'] = df[column].apply(rule)
现在调用apply_rule
apply_rule(df, greater_than_mean_plus_1_std, "col1")