Python 使用None初始化数据帧
我很难创建一个没有值的数据帧。 为此,我执行了几个步骤,但我相信使用pandas函数可以得到相同的结果Python 使用None初始化数据帧,python,pandas,dataframe,Python,Pandas,Dataframe,我很难创建一个没有值的数据帧。 为此,我执行了几个步骤,但我相信使用pandas函数可以得到相同的结果 mydata = [] mydata.append([None, None, None, None]) mydata = np.array(mydata) mydata = pd.DataFrame(mydata, columns='Start','End','Duration']) 是否有获得相同结果的命令?我认为您需要从列表创建numpy数组: mydata = pd.DataFr
mydata = []
mydata.append([None, None, None, None])
mydata = np.array(mydata)
mydata = pd.DataFrame(mydata, columns='Start','End','Duration'])
是否有获得相同结果的命令?我认为您需要从列表创建numpy数组
:
mydata = pd.DataFrame(np.array([None, None, None]).reshape(-1,3),
columns=['Start','End','Duration'])
print (mydata)
Start End Duration
0 None None None
另一个具有[[]]
的slowier解决方案:
mydata = pd.DataFrame([[None, None, None]], columns=['Start','End','Duration'])
print (mydata)
Start End Duration
0 None None None
如果使用列
和索引
值,则所有数据都是NaN
,并且可以无
:
print (pd.DataFrame(columns=['Start','End','Duration'], index=[0]))
Start End Duration
0 NaN NaN NaN
mydata = pd.DataFrame(columns=['Start','End','Duration'], index=[0]).replace({np.nan:None})
print (mydata)
Start End Duration
0 None None None
我想您需要从列表创建numpy数组
:
mydata = pd.DataFrame(np.array([None, None, None]).reshape(-1,3),
columns=['Start','End','Duration'])
print (mydata)
Start End Duration
0 None None None
另一个具有[[]]
的slowier解决方案:
mydata = pd.DataFrame([[None, None, None]], columns=['Start','End','Duration'])
print (mydata)
Start End Duration
0 None None None
如果使用列
和索引
值,则所有数据都是NaN
,并且可以无
:
print (pd.DataFrame(columns=['Start','End','Duration'], index=[0]))
Start End Duration
0 NaN NaN NaN
mydata = pd.DataFrame(columns=['Start','End','Duration'], index=[0]).replace({np.nan:None})
print (mydata)
Start End Duration
0 None None None
另一种方法是:
pd.DataFrame({'Start':[None],'End':[None],'Duration':[None]})
另一种方法是:
pd.DataFrame({'Start':[None],'End':[None],'Duration':[None]})
这是一个快速的一行:
>>> pd.DataFrame(np.empty((4,3),dtype=pd.Timestamp),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
>>> pd.DataFrame(np.empty((2,3))*np.nan,columns=['Start','End','Duration'])
Start End Duration
0 NaN NaN NaN
1 NaN NaN NaN
一般情况下,一艘班轮应为:
>>> pd.DataFrame(np.empty((5,3),dtype=object),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
4 None None None
这是一条一号班轮:
>>> pd.DataFrame(np.empty((4,3),dtype=pd.Timestamp),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
>>> pd.DataFrame(np.empty((2,3))*np.nan,columns=['Start','End','Duration'])
Start End Duration
0 NaN NaN NaN
1 NaN NaN NaN
这是一个快速的一行:
>>> pd.DataFrame(np.empty((4,3),dtype=pd.Timestamp),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
>>> pd.DataFrame(np.empty((2,3))*np.nan,columns=['Start','End','Duration'])
Start End Duration
0 NaN NaN NaN
1 NaN NaN NaN
一般情况下,一艘班轮应为:
>>> pd.DataFrame(np.empty((5,3),dtype=object),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
4 None None None
这是一条一号班轮:
>>> pd.DataFrame(np.empty((4,3),dtype=pd.Timestamp),columns=['Start','End','Duration'])
Start End Duration
0 None None None
1 None None None
2 None None None
3 None None None
>>> pd.DataFrame(np.empty((2,3))*np.nan,columns=['Start','End','Duration'])
Start End Duration
0 NaN NaN NaN
1 NaN NaN NaN