python function missing 2 required positional arguments: ln1, ln2

Question

def di(l1,l2, ln1, ln2):  
   dlt = (l2-l1)
   dln = (ln2-ln1)    
   d = dlt * dln
return d

abc = newdf[['l1','l2','ln1','ln2']]
abc.columns

Function working without errors. But while working on dataframe, it showing error as

di() missing 2 required positional arguments: ln1, ln2

newdf = newdf.withColumn('newcolnm',reduce(di, ( newdf[col] for col in abc.columns ) ))

Answer 1

Your function definition is correct but when calling the function you arent passing requited 4 arguments. your calling should be like funct(a, b, c, d)

if you don't want parameters compulsory define your function as

di (p1=None, p2=None, p3=None, p4=None)

with this you can omit unwanted parameters