如何添加新列以触发数据框取决于multipme现有列？

Question

I am going to add new column to a dataframe. for example, I have a dataframe df

    id|c_1         |c_2          |c_3       |c_4    |.......|c_200    |c_tot
    1 |[1,2,3,5]   |[t,4,bv,55,2]|[]        |[1,22] |       |[k,v,c,x]|[1,2,3,4,5,t,bv,55,22,k,v,c,x]
    2 |[1,2,4]     |[4,3,8]      |[6,7]     |[10,12]        | [11]    |[1,2,3,4,6,7,8,10,11,12]
    .
    .

I want to get some statistique from my dataframe, for example I want a new column that contain Entropy for each id so we must calculate pi for each c_i and then calculate entropy

    pi=(size(c_i)+1))/(size(c_tot)+1)
    Entropy=-sum(pi*ln(pi))   \\i in[1,200]

for example for the first value of the new column entropy must be

    entropy=-((5/14*ln(5/14))+(6/14*ln(6/14))+(1/14*ln(1/14)).... +(5/14)*ln(5/14))

I know that i can work with expression link but don't found idea for the expression because i have multiple column.

Answer 1

Your expression can be slightly simplified to:

To generate that in Scala:

entropy = (1 to 200).toSeq
                    .map(c => s" ( size(c_$c) + 1 ) * ln( (size(c_$c) + 1) / (size(c_tot) + 1) ) ")
                    .mkString("-(" , "+" , ") / size(c_tot) ")

And then use it with expr

df.withColumn("entropy" , expr(entropy) )