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

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!

其他回答

简单的条件:

if any(str(elem) in ['a','b'] for elem in df['column'].tolist()):

或者用级数。tolist或Series.any:

>>> s = pd.Series(list('abc'))
>>> s
0    a
1    b
2    c
dtype: object
>>> 'a' in s.tolist()
True
>>> (s=='a').any()
True

系列。tolist做了一个关于一个系列的列表,而另一个我只是从一个常规系列中获得一个布尔系列,然后检查是否有任何真布尔系列。

假设你的数据框架是这样的:

现在你要检查文件名“80900026941984”是否存在于数据帧中。

你可以简单地写:

if sum(df["filename"].astype("str").str.contains("80900026941984")) > 0:
    print("found")

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

你可以试着检查一个名为“id”的列中的特定值“x”

if x in df['id'].values