Pandas - 手动创建数据框并插入值
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/32814746/
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
Pandas - create dataframe manually and insert values
提问by user1700890
Here is my code:
这是我的代码：
import pandas as pd
df = pd.DataFrame(columns = ["A", "B"])
df.iloc[0]['A'] = 5
Here is output:
这是输出：
Traceback (most recent call last):
File "K:/Dop/Pentas/Simpletest/Temp.py", line 38, in <module>
df.iloc[0]['A'] = 5
File "C:\Python34\lib\site-packages\pandas\core\indexing.py", line 1189, in __getitem__
return self._getitem_axis(key, axis=0)
File "C:\Python34\lib\site-packages\pandas\core\indexing.py", line 1480, in _getitem_axis
return self._get_loc(key, axis=axis)
File "C:\Python34\lib\site-packages\pandas\core\indexing.py", line 89, in _get_loc
return self.obj._ixs(key, axis=axis)
File "C:\Python34\lib\site-packages\pandas\core\frame.py", line 1719, in _ixs
label = self.index[i]
File "C:\Python34\lib\site-packages\pandas\core\index.py", line 1076, in __getitem__
return getitem(key)
IndexError: index 0 is out of bounds for axis 0 with size 0
Any suggestions on how to fix it? I do not know overall size of my dataframe before hand, but I can guess.
有关如何修复它的任何建议？我事先不知道我的数据框的整体大小，但我可以猜测。
回答by hellpanderr
You can either initialize dataframe with data using
您可以使用数据初始化数据帧
df = pd.DataFrame(columns=["A", "B"], data=[[5,np.nan]]),
df = pd.DataFrame(columns=["A", "B"], data=[[5,np.nan]]),
or use set_valuemethod (which is much faster than ilocby the way):
df.set_value(0,'A',5)
或者使用set_value方法（比iloc顺便说的快得多）：
df.set_value(0,'A',5)
UPDATE 2018-04-12?
更新 2018-04-12？
Since pandas version 0.21.0 df.set_valueis deprecated. You should use .at[]or .iat[]accessors instead:
由于Pandas版本 0.21.0df.set_value已弃用。您应该使用.at[]or.iat[]访问器：
df.at[0, 'A'] = 5
回答by MhP
Providing a sample to increase your data frame dynamically... sizeOfDataFrame variable just limits for loop which adds data to the dataframe and is dynamic...
提供一个示例来动态增加您的数据框... sizeOfDataFrame 变量只是限制循环，它将数据添加到数据框并且是动态的...
import pandas as pd
import numpy as np
yourDataFrame = pd.DataFrame()
sizeOfDataFrame = np.random.randint(100, size=1)
for currentLine in range(sizeOfDataFrame):
yourDataFrame = yourDataFrame.append(pd.DataFrame({"A":np.random.randint(100, size=1),"B":np.random.randint(100, size=1),"C":np.random.randint(100, size=1)},index=[0]))
yourDataFrame.reset_index(inplace = True)
yourDataFrame.drop('index',axis=1,inplace=True)
