Python ValueError：<something> 的石斑鱼不是一维的
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ValueError: Grouper for <something> not 1-dimensional
提问by Shahar
I'm have the following code which creates a table and a barplot via seaborn.
我有以下代码，它通过 seaborn 创建一个表格和一个条形图。
#Building a dataframe grouped by the # of Engagement Types
sales_type = sales.groupby('# of Engagement Types').sum()
#Calculating the % of people who bought the course by # engagement types
sales_type['% Sales per Participants'] = round(100*(sales_type['Sales'] / sales_type['Had an Engagement']), 2)
#Calculating the # of people who didn't have any engagements
sales_type.set_value(index=0, col='Had an Engagement', value=sales[sales['Had an Engagement']==0].count()['Sales'])
#Calculating the % of sales for those who didn't have any engagements
sales_type.set_value(index=0, col='% Sales per Participants',
value=round(100 * (sales_type.ix[0, 'Sales'] /
sales[sales['Had an Engagement']==0].count()['Sales']),2))
#Setting the graph image
fig, (ax1) = plt.subplots(nrows=1, ncols=1, figsize=(12,4))
sns.set_style("whitegrid")
# Ploting the histagram for the % of total prospects
ax1 = sns.barplot(x=sales_type.index,y='% Sales per Participants', data=sales_type ,ax=ax1)
ax1.set(ylabel = '%')
ax1.set_title('% Sales per Participants By # of Engagement Types')
#present the table
sales_type.xs(['Had an Engagement', 'Sales','% Sales per Participants'],axis=1).transpose()
#sales_type
I'm using the same code concept for other parameters I have with no issue. However, for one parameter I get an error: "ValueError: Grouper for '' not 1-dimensional" for the line code:
我对其他参数使用相同的代码概念，我没有问题。但是，对于一个参数，我收到一个错误：“ValueError: Grouper for '' not 1-dimensional” 行代码：
ax1 = sns.barplot(x=sales_type.index,y='% Sales per Participants', data=sales_type ,ax=ax1)
This error occurs although the dataframe doesn't have more than one dimension.
尽管数据帧的维度不超过一维，但会发生此错误。
This is the head of the table:
这是表的头：
Sales Pre-Ordered / Ordered Book \
# of Engagement Types
0 1.0 0.0
1 20.0 496.0
2 51.0 434.0
3 82.0 248.0
4 71.0 153.0
5 49.0 97.0
6 5.0 24.0
Opted In For / Clicked to Kindle Viewed PLC \
# of Engagement Types
0 0.0 0
1 27034.0 5920
2 6953.0 6022
3 1990.0 1958
4 714.0 746
5 196.0 204
6 24.0 24
# of PLC Engagement Viewed Webinar \
# of Engagement Types
0 0.0 0
1 6434.0 1484
2 7469.0 1521
3 2940.0 1450
4 1381.0 724
5 463.0 198
6 54.0 24
# of Webinars (Live/Replay) \
# of Engagement Types
0 0.0
1 1613.0
2 1730.0
3 1768.0
4 1018.0
5 355.0
6 45.0
OCCC Facebook Group Member Engaged in Cart-Open \
# of Engagement Types
0 0.0 0
1 148.0 160
2 498.0 1206
3 443.0 967
4 356.0 511
5 168.0 177
6 24.0 24
# of Engagement at Cart Open Had an Engagement \
# of Engagement Types
0 0.0 3387
1 189.0 35242
2 1398.0 8317
3 1192.0 2352
4 735.0 801
5 269.0 208
6 40.0 24
Total # of Engagements % Sales per Participants
# of Engagement Types
0 0.0 0.03
1 35914.0 0.06
2 18482.0 0.61
3 8581.0 3.49
4 4357.0 8.86
5 1548.0 23.56
6 211.0 20.83
This is the full error:
这是完整的错误：
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-211-f0185fe64c1a> in <module>()
12 sns.set_style("whitegrid")
13 # Ploting the histagram for the % of total prospects
---> 14 ax1 = sns.barplot(x=sales_type.index,y='% Sales per Participants', data=sales_type ,ax=ax1)
15 ax1.set(ylabel = '%')
16 ax1.set_title('% Sales per Participants By # of Engagement Types')
ValueError: Grouper for '<class 'pandas.core.frame.DataFrame'>' not 1-dimensional
I've tried to search the internet and Stack Overflow for this error, but got no results. Does anyone has an idea what's going on?
我试图在互联网和 Stack Overflow 上搜索此错误，但没有结果。有谁知道发生了什么？
回答by firelynx
Simplified problem
简化问题
I also ran into this problem, and found the cause of it and the obvious solution
我也遇到了这个问题，找到了原因和明显的解决办法
To recreate this:
要重新创建这个：
df = pd.DataFrame({"foo": [1,2,3], "bar": [1,2,3]})
df.rename(columns={'foo': 'bar'}, inplace=True)
bar bar
0 1 1
1 2 2
2 3 3
df.groupby('bar')
ValueError: Grouper for 'bar' not 1-dimensional
Just like a lot of cryptic pandas errors, this one too stems from having two columns with the same name.
就像许多神秘的熊猫错误一样，这个错误也源于有两列同名。
Figure out which one you want to use, rename or drop the other column and redo the operation.
确定您要使用哪一列，重命名或删除另一列并重做操作。
Solution
解决方案
Rename the columns like this
像这样重命名列
df.columns = ['foo', 'bar']
foo bar
0 1 1
1 2 2
2 3 3
df.groupby('bar')
<pandas.core.groupby.DataFrameGroupBy object at 0x1066dd950>
回答by w-m
Happened to me when I accidentally created MultiIndex columns:
当我不小心创建 MultiIndex 列时发生在我身上：
>>> values = np.asarray([[1, 1], [2, 2], [3, 3]])
# notice accidental double brackets around column list
>>> df = pd.DataFrame(values, columns=[["foo", "bar"]])
# prints very innocently
>>> df
foo bar
0 1 1
1 2 2
2 3 3
# but throws this error
>>> df.groupby("foo")
ValueError: Grouper for 'foo' not 1-dimensional
# cause:
>>> df.columns
MultiIndex(levels=[['bar', 'foo']],
labels=[[1, 0]])
# fix by using correct columns list
>>> df = pd.DataFrame(values, columns=["foo", "bar"])
>>> df.groupby("foo")
<pandas.core.groupby.groupby.DataFrameGroupBy object at 0x7f9a280cbb70>
回答by moto
Something to add to @w-m's answer.
要添加到@wm 的答案中。
If you are adding multiple columns from one dataframe to another:
如果您要将一个数据帧中的多列添加到另一个数据帧：
df1[['col1', 'col2']] = df2[['col1', 'col2']]
it will create a multi-column index and if you try to group by anything on df1, it will give you this error.
它将创建一个多列索引，如果您尝试按任何内容进行分组df1，则会出现此错误。
To solve this, get rid of the multi-index by using
要解决这个问题，请使用删除多索引
df1.columns = df1.columns.get_level_values(0)
