pandas 解决重新索引仅对唯一值的索引对象有效
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Resolving Reindexing only valid with uniquely valued Index objects
提问by Paul
I have viewed many of the questions that come up with this error. I am running pandas '0.10.1'
我已经查看了许多与此错误相关的问题。我正在运行Pandas“0.10.1”
df = DataFrame({'A' : np.random.randn(5),
'B' : np.random.randn(5),'C' : np.random.randn(5),
'D':['a','b','c','d','e'] })
#gives error
df.take([2,0,1,2,3], axis=1).drop(['C'],axis=1)
#works fine
df.take([2,0,1,2,1], axis=1).drop(['C'],axis=1)
Only thing I can see is that in the former case I have the non-numeric column, which seems to be affecting the index somehow but the below command returns empty:
我唯一能看到的是，在前一种情况下，我有非数字列，这似乎以某种方式影响了索引，但以下命令返回空：
df.take([2,0,1,2,3], axis=1).index.get_duplicates()
Reindexing error makes no sensedoes not seem to apply as my old index is unique.
重新索引错误似乎不适用，因为我的旧索引是唯一的。
My index appears unique as far as I can tell using this command df.take([2,0,1,2,3], axis=1).index.get_duplicates() from this Q&A: problems with reindexing dataframes: Reindexing only valid with uniquely valued Index objects
：我可以告诉使用该命令df.take（[2,0,1,2,3]，轴= 1）从该Q＆A .index.get_duplicates（）我的索引显示为远独特与重新索引dataframes问题：只重新编制索引对唯一值的索引对象有效
"Reindexing only valid with uniquely valued Index objects"does not seem to apply
“重新索引仅对唯一值的索引对象有效”似乎不适用
I think my pandas version# is ok so this should bug should not be the problem pandas Reindexing only valid with uniquely valued Index objects
我认为我的Pandas版本# 没问题，所以这应该不是问题Pandas重新索引仅对唯一值的索引对象有效
回答by simple
Firstly, I believe you meant to test for duplicates using the following command:
首先，我相信您打算使用以下命令测试重复项：
df.take([2,0,1,2,3],axis=1).columns.get_duplicates()
because if you used index instead of columns, then it would obviously returned an empty array because the random float values don't repeat. The above command returns, as expected:
因为如果您使用索引而不是列，那么它显然会返回一个空数组，因为随机浮点值不会重复。上面的命令按预期返回：
['C']
Secondly, I think you're right, the non-numeric column is throwing it off, because even if you use the following, there is still an error:
其次，我认为您是对的，非数字列将其丢弃，因为即使您使用以下内容，仍然存在错误：
df = DataFrame({'A' : np.random.randn(5), 'B' : np.random.randn(5),'C' :np.random.randn(5), 'D':[str(x) for x in np.random.randn(5) ]})
It could be a bug, because if you check out the core file called 'index.py', on line 86, and line 1228, the type it is expecting is either (respectively):
这可能是一个错误，因为如果您在第 86 行和第 1228 行查看名为“index.py”的核心文件，它所期望的类型是（分别）：
_engine_type = _index.ObjectEngine
_engine_type = _index.Int64Engine
and neither of those seem to be expecting a string, if you look deeper into the documentation. That's the best I got, good luck!! Let me know if you solve this as I'm interested too.
如果您更深入地查看文档，那么这些似乎都不需要字符串。这是我得到的最好的，祝你好运！！如果您解决了这个问题，请告诉我，因为我也很感兴趣。
