I am trying to determine whether there is an entry in a Pandas column that has a particular value. I tried to do this with if x in df['id']. I thought this was working, except when I fed it a value that I knew was not in the column 43 in df['id'] it still returned True. When I subset to a data frame only containing entries matching the missing id df[df['id'] == 43] there are, obviously, no entries in it. How to I determine if a column in a Pandas data frame contains a particular value and why doesn't my current method work? (FYI, I have the same problem when I use the implementation in this answer to a similar question).
当前回答
Use
df[df['id']==x].index.tolist()
如果x存在于id中，那么它将返回它所在位置的索引列表，否则它将给出一个空列表。
其他回答
简单的条件:
if any(str(elem) in ['a','b'] for elem in df['column'].tolist()):
你也可以使用pandas.Series.isin，尽管它比s.values中的'a'长一点:
In [2]: s = pd.Series(list('abc'))
In [3]: s
Out[3]:
0 a
1 b
2 c
dtype: object
In [3]: s.isin(['a'])
Out[3]:
0 True
1 False
2 False
dtype: bool
In [4]: s[s.isin(['a'])].empty
Out[4]: False
In [5]: s[s.isin(['z'])].empty
Out[5]: True
但是，如果您需要为一个DataFrame同时匹配多个值，这种方法可以更加灵活。
>>> df = DataFrame({'A': [1, 2, 3], 'B': [1, 4, 7]})
>>> df.isin({'A': [1, 3], 'B': [4, 7, 12]})
A B
0 True False # Note that B didn't match 1 here.
1 False True
2 True True
我有一个CSV文件要读取:
df = pd.read_csv('50_states.csv')
在尝试之后:
if value in df.column:
print(True)
即使值在列中，它也不会输出true;
我试着:
for values in df.column:
if value == values:
print(True)
#Or do something
else:
print(False)
这工作。希望这能有所帮助!
使用query()查找符合条件的行，并获得形状为[0]的行数。如果存在至少一个条目，则此语句为True:
df.query('id == 123').shape[0] > 0
Use
df[df['id']==x].index.tolist()
如果x存在于id中，那么它将返回它所在位置的索引列表，否则它将给出一个空列表。
