Skip to content

List Frequency Sorting

Routine Summary Inputs Outputs Variables Used Author
Sorts a list based on frequency, then by value L₁ - A list to be sorted L₁ - The original list, sorted by frequency of elements L₁, L₂, L₃ Trenly 
SortD(L₁
DelVar L₂DelVar L₃
SetUpEditor
For(θ,1,dim(L₁
L₁(θ→L₂(1+dim(L₂
sum(L₁=Ans→L₃(dim(L₂
θ-1+Ans→θ
End
DelVar L₁
SetUpEditor
While dim(L₂
1+sum(not(cumSum(L₃=max(L₃→θ
L₃(θ)→N
For(E,1,N
L₂(θ→L₁(1+dim(L₁
End
For(E,θ+1,dim(L₂
L₂(E→L₂(E-1
L₃(E→L₃(E-1
End
dim(L₂)-1→dim(L₂
dim(L₃)-1→dim(L₃
End

This routine uses the List Frequency routine to find the frequency of each number. It then deletes, and reconstructs L₁ from the values in those lists by searching for the highest frequency, then adding it into L₁ the number of times it occurs. It then shifts the elements inside the frequency lists above the value down 1, overwriting the value which was just inserted into L₁. It then decreases the length of the frequency lists, and repeats until there are no more values to be added. This routine automatically cleans up, leaving L₂ and L₃ empty. If you wish to sort in ascending frequency, change the max( on line 12 to min(. If you wish to sort the values in ascending order instead of descending order, change the SortD( on line 1 to SortA(

Error Conditions

Authors: KG