Deedle使用默认值在框架中分配系列

如何解决Deedle使用默认值在框架中分配系列

我有一个熊猫脚本，正在转换为C＃deedle，但无法设置初始值。

#Python Pandas
dat['processorIndex'] = dat['MSAIndex']
dat['opportunityIndex'] = ''
dat['nvdSerialPrefix'] = ''
dat['saleyardNo'] = ''
dat['ownerProducer'] = dat['Producer']
dat['Species'] = 'Bovine'
dat['coldGrader'] = dat['Grader']
dat['hotGrader'] = dat['Grader']

现在C＃端：

C# deedle
// Assign some of the new fields
df["processorIndex"] = df["MSAIndex"];
df["nvdSerialPrefix"] = ""; // Does not work
df["saleyardNo"] = ""; // Does not work
df["ownerProducer"] = ""; // Does not work
df["Species"] = df["Species"].SelectValues((string s) => "Bovine"); // Does not work
df["coldGrader"] = df["Grader"];
df["hotGrader"] = df["Grader"]; 

如何创建新列并设置初始值？