Python 为什么我得到：“值的长度与索引的长度不匹配”错误？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/35599256/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Why do I get: "Length of values does not match length of index" error?
提问by Alexander UpUp
I have the following code and I'm trying to assign Trueto a new Column where Actual Date equals the Date in Column 'D' (Date created) and Falseto any other.
我有以下代码，我试图分配True给一个新列，其中实际日期等于列“D”（创建日期）中的日期和False任何其他列。
I'm quite new to Python so I would like to understand what I have done wrong:
我对 Python 很陌生，所以我想了解我做错了什么：
def GetData():
myList = GetFileList(TodaysDate,5)
NewDataFrame = pd.DataFrame()
for x in myList:
#The date of the actuals data is the day BEFORE it was created
ActualDate = getDate(x) - timedelta(days=1)
myTempData = pd.read_csv(WSIWeatherDir + "\" + x, parse_dates = [" date"], date_parser = DateTimeParser)
myTempData = myTempData.replace(-99,np.nan)
myTempData = myTempData.loc[myTempData['name'].isin(NL_WeatherStations)]
myTempData['D'] = myTempData[' date'].dt.date
#MyData = myTempData.sort([' date'], ascending=True)
#print MyData
#Select indices of the weather file where the column " date" is equal to the actual date we are looking for
MyActualIndex = myTempData['D'] == ActualDate
MyActualData = myTempData[MyActualIndex]
MyExpectedIndex = myTempData.index.difference(MyActualData.index)
MyExpectedData = myTempData.loc[MyExpectedIndex]
myTempData ['Actuals'] = [True] * len(MyActualData.index)
myTempData ['Actuals'] = [False] * len(MyExpectedData.index)
NewDataFrame = pd.concat([NewDataFrame,myTempData])
return NewDataFrame
print GetData()
Error
错误
runfile('C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py', wdir='C:/Users//Desktop/NLG_TAC_Calculation')
Traceback (most recent call last):
File "<ipython-input-4-c9c151bca95a>", line 1, in <module>
runfile('C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py', wdir='C:/Users//Desktop/NLG_TAC_Calculation')
File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 685, in runfile
execfile(filename, namespace)
File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 71, in execfile
exec(compile(scripttext, filename, 'exec'), glob, loc)
File "C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py", line 117, in <module>
print GetData()
File "C:/Users//Desktop/NLG_TAC_Calculation/TAC_2.py", line 108, in GetData
myTempData ['Actuals'] = [True] * len(MyActualData.index)
File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2127, in __setitem__
self._set_item(key, value)
File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2204, in _set_item
value = self._sanitize_column(key, value)
File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 2362, in _sanitize_column
value = _sanitize_index(value, self.index, copy=False)
File "C:\Python27\lib\site-packages\pandas\core\series.py", line 2579, in _sanitize_index
raise ValueError('Length of values does not match length of '
ValueError: Length of values does not match length of index
采纳答案by Matheus Portela
My best guess relies in this part:
我最好的猜测依赖于这一部分：
myTempData ['Actuals'] = [True] * len(MyActualData.index)
myTempData ['Actuals'] = [False] * len(MyExpectedData.index)
It first says that myTempData['Actuals']is a column of size len(MyActualData.index)containing only Truevalues. Next, it replaces everything by another column of size len(MyExpectedData.index)(which I expect to be different) containing Falsevalues.
它首先说这myTempData['Actuals']是一个len(MyActualData.index)只包含True值的大小列。接下来，它将所有内容替换len(MyExpectedData.index)为包含False值的另一列大小（我预计会有所不同）。
You can first create a column of Truevalues and, only then, replace Falseones:
您可以先创建一列True值，然后才替换False这些值：
myTempData['Actuals'] = True
myTempData.iloc[MyExpectedIndex] = False
