Python ValueError：必须仅传递带有布尔值的 DataFrame
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ValueError: Must pass DataFrame with boolean values only
提问by Umang Mistry
Question
题
In this datafile, the United States is broken up into four regions using the "REGION" column.
在此数据文件中，使用“REGION”列将美国分为四个区域。
Create a query that finds the counties that belong to regions 1 or 2, whose name starts with 'Washington', and whose POPESTIMATE2015 was greater than their POPESTIMATE 2014.
创建一个查询，查找属于区域 1 或 2、名称以“Washington”开头且 POPESTIMATE2015 大于其 POPESTIMATE 2014 的县。
This function should return a 5x2 DataFrame with the columns = ['STNAME', 'CTYNAME'] and the same index ID as the census_df (sorted ascending by index).
此函数应返回一个 5x2 数据帧，其中列 = ['STNAME', 'CTYNAME'] 和与 census_df 相同的索引 ID（按索引升序排序）。
CODE
代码
def answer_eight():
counties=census_df[census_df['SUMLEV']==50]
regions = counties[(counties[counties['REGION']==1]) | (counties[counties['REGION']==2])]
washingtons = regions[regions[regions['COUNTY']].str.startswith("Washington")]
grew = washingtons[washingtons[washingtons['POPESTIMATE2015']]>washingtons[washingtons['POPESTIMATES2014']]]
return grew[grew['STNAME'],grew['COUNTY']]
outcome = answer_eight()
assert outcome.shape == (5,2)
assert list (outcome.columns)== ['STNAME','CTYNAME']
print(tabulate(outcome, headers=["index"]+list(outcome.columns),tablefmt="orgtbl"))
ERROR
错误
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-77-546e58ae1c85> in <module>()
6 return grew[grew['STNAME'],grew['COUNTY']]
7
----> 8 outcome = answer_eight()
9 assert outcome.shape == (5,2)
10 assert list (outcome.columns)== ['STNAME','CTYNAME']
<ipython-input-77-546e58ae1c85> in answer_eight()
1 def answer_eight():
2 counties=census_df[census_df['SUMLEV']==50]
----> 3 regions = counties[(counties[counties['REGION']==1]) | (counties[counties['REGION']==2])]
4 washingtons = regions[regions[regions['COUNTY']].str.startswith("Washington")]
5 grew = washingtons[washingtons[washingtons['POPESTIMATE2015']]>washingtons[washingtons['POPESTIMATES2014']]]
/opt/conda/lib/python3.5/site-packages/pandas/core/frame.py in __getitem__(self, key)
1991 return self._getitem_array(key)
1992 elif isinstance(key, DataFrame):
-> 1993 return self._getitem_frame(key)
1994 elif is_mi_columns:
1995 return self._getitem_multilevel(key)
/opt/conda/lib/python3.5/site-packages/pandas/core/frame.py in _getitem_frame(self, key)
2066 def _getitem_frame(self, key):
2067 if key.values.size and not com.is_bool_dtype(key.values):
-> 2068 raise ValueError('Must pass DataFrame with boolean values only')
2069 return self.where(key)
2070
ValueError: Must pass DataFrame with boolean values only
I am clueless. Where am I going wrong?
我一窍不通。我哪里错了？
Thanks
谢谢
采纳答案by EdChum
You're trying to use a different shaped df to mask your df, this is wrong, additionally the way you're passing the conditions is being used incorrectly. When you compare a column or series in a df with a scalar to produce a boolean mask you should pass just the condition, not use this successively.
您正在尝试使用不同形状的 df 来掩盖您的 df，这是错误的，另外您传递条件的方式使用不正确。当您将 df 中的列或系列与标量进行比较以生成布尔掩码时，您应该只传递条件，而不是连续使用它。
def answer_eight():
counties=census_df[census_df['SUMLEV']==50]
# this is wrong you're passing the df here multiple times
regions = counties[(counties[counties['REGION']==1]) | (counties[counties['REGION']==2])]
# here you're doing it again
washingtons = regions[regions[regions['COUNTY']].str.startswith("Washington")]
# here you're doing here again also
grew = washingtons[washingtons[washingtons['POPESTIMATE2015']]>washingtons[washingtons['POPESTIMATES2014']]]
return grew[grew['STNAME'],grew['COUNTY']]
you want:
你要：
def answer_eight():
counties=census_df[census_df['SUMLEV']==50]
regions = counties[(counties['REGION']==1]) | (counties['REGION']==2])]
washingtons = regions[regions['COUNTY'].str.startswith("Washington")]
grew = washingtons[washingtons['POPESTIMATE2015']>washingtons['POPESTIMATES2014']]
return grew[['STNAME','COUNTY']]
回答by gourav chatterjee
def answer_eight():
df=census_df[census_df['SUMLEV']==50]
#df=census_df
df=df[(df['REGION']==1) | (df['REGION']==2)]
df=df[df['CTYNAME'].str.startswith('Washington')]
df=df[df['POPESTIMATE2015'] > df['POPESTIMATE2014']]
df=df[['STNAME','CTYNAME']]
print(df.shape)
return df.head(5)
回答by yogs
def answer_eight():
county = census_df[census_df['SUMLEV']==50]
req_col = ['STNAME','CTYNAME']
region = county[(county['REGION']<3) & (county['POPESTIMATE2015']>county['POPESTIMATE2014']) & (county['CTYNAME'].str.startswith('Washington'))]
region = region[req_col]
return region
answer_eight()
