案例1個合併如何連接兩個DataFrames並與多個主鍵更新涉及遺漏值?
舊數據框:
## +---+----+----+---+
## |pk1|pk2|val1|val2|
## +---+----+----+---+
## | 1| aa| ab| ac|
## | 2| bb| bc| bd|
## +---+----+----+---+
新數據框中:
## +---+----+----+---+
## |pk1|pk2|val1|val2|
## +---+----+----+---+
## | 1| aa| ab| ad|
## | 2| bb| bb| bd|
## | 3| cc| cc| cc|
## +---+----+----+---+
結果:
## +---+----+----+---+
## |pk1|pk2|val1|val2|
## +---+----+----+---+
## | 1| aa| ab| ad|
## | 2| bb| bb| bd|
## | 3| cc| cc| cc|
## +---+----+----+---+
是否外與多個鍵加入是否行得通呢?
是怎樣的結果數據集從數據幀新的不同? –