我的数据如下-
tag1 tag2 tag3 originalNumber
A sat nov
A sat jan 1
A sat feb
A sat mar
A sun jan 2
A sun dec
B abc cde 1
B abc bde
B abc fde
B ebc cde 2
现在我正尝试创建一个新列，如果originalNumber为空，则获取最后一个非空的originalNumber可用。例如-
tag1 tag2 tag3 originalNumber newNumber
A sat nov
A sat jan 1 1
A sat feb 1
A sat mar 1
A sun jan 2 2
A sun dec 2
B abc cde 1 1
B abc bde 1
B abc fde 1
B ebc cde 2 2