Flatten all inner lists that do not have sublists

Clash Royale CLAN TAG#URR8PPP

up vote
3
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As the title says, I would like to flatten all inner lists, excluded the ones that do not have sublists. For example, from

lis = a, b, d, f, c, k, h, l, e, a;

I would like to have

myFlatten[lis]

a, b, d, f, c, k, h, l, e, a

I have a solution, but probably is inefficient and not elegant.
The steps are the following:

• change the Head of all List subparts that do not have members of type List, to something else, say myList
  


• 
  Flatten the resulting expression


• change back myList to List
  

this is my implementation:

notListQ[z_] := Head[z] =!= List;

myFlatten[list_List] := Module[myList, tempList,
 tempList = list /. List[y__?notListQ] -> myList[y];
 tempList = Flatten[tempList];
 tempList /. myList -> List
]

This obviously can be shortened to

myFlatten[list_List] := Module[myList,
 Flatten[list /. List[y__?notListQ] -> myList[y]] /. myList -> List
]

Any errors in my implementation?

Better solutions?

Thank you

list-manipulation

share|improve this question

asked 38 mins ago

enzotib

477415

add a comment | 

up vote
3
down vote

favorite

1

As the title says, I would like to flatten all inner lists, excluded the ones that do not have sublists. For example, from

lis = a, b, d, f, c, k, h, l, e, a;

I would like to have

myFlatten[lis]

a, b, d, f, c, k, h, l, e, a

I have a solution, but probably is inefficient and not elegant.
The steps are the following:

• change the Head of all List subparts that do not have members of type List, to something else, say myList
  


• 
  Flatten the resulting expression


• change back myList to List
  

this is my implementation:

notListQ[z_] := Head[z] =!= List;

myFlatten[list_List] := Module[myList, tempList,
 tempList = list /. List[y__?notListQ] -> myList[y];
 tempList = Flatten[tempList];
 tempList /. myList -> List
]

This obviously can be shortened to

myFlatten[list_List] := Module[myList,
 Flatten[list /. List[y__?notListQ] -> myList[y]] /. myList -> List
]

Any errors in my implementation?

Better solutions?

Thank you

list-manipulation

share|improve this question

asked 38 mins ago

enzotib

477415

add a comment | 

up vote
3
down vote

favorite

1

up vote
3
down vote

favorite

1

1

As the title says, I would like to flatten all inner lists, excluded the ones that do not have sublists. For example, from

lis = a, b, d, f, c, k, h, l, e, a;

I would like to have

myFlatten[lis]

a, b, d, f, c, k, h, l, e, a

I have a solution, but probably is inefficient and not elegant.
The steps are the following:

• change the Head of all List subparts that do not have members of type List, to something else, say myList
  


• 
  Flatten the resulting expression


• change back myList to List
  

this is my implementation:

notListQ[z_] := Head[z] =!= List;

myFlatten[list_List] := Module[myList, tempList,
 tempList = list /. List[y__?notListQ] -> myList[y];
 tempList = Flatten[tempList];
 tempList /. myList -> List
]

This obviously can be shortened to

myFlatten[list_List] := Module[myList,
 Flatten[list /. List[y__?notListQ] -> myList[y]] /. myList -> List
]

Any errors in my implementation?

Better solutions?

Thank you

list-manipulation

share|improve this question

asked 38 mins ago

enzotib

477415

As the title says, I would like to flatten all inner lists, excluded the ones that do not have sublists. For example, from

lis = a, b, d, f, c, k, h, l, e, a;

I would like to have

myFlatten[lis]

a, b, d, f, c, k, h, l, e, a

I have a solution, but probably is inefficient and not elegant.
The steps are the following:

• change the Head of all List subparts that do not have members of type List, to something else, say myList
  


• 
  Flatten the resulting expression


• change back myList to List
  

this is my implementation:

notListQ[z_] := Head[z] =!= List;

myFlatten[list_List] := Module[myList, tempList,
 tempList = list /. List[y__?notListQ] -> myList[y];
 tempList = Flatten[tempList];
 tempList /. myList -> List
]

This obviously can be shortened to

myFlatten[list_List] := Module[myList,
 Flatten[list /. List[y__?notListQ] -> myList[y]] /. myList -> List
]

Any errors in my implementation?

Better solutions?

Thank you

list-manipulation

list-manipulation

share|improve this question

asked 38 mins ago

enzotib

477415

share|improve this question

asked 38 mins ago

enzotib

477415

share|improve this question

share|improve this question

asked 38 mins ago

enzotib

477415

asked 38 mins ago

enzotib

477415

asked 38 mins ago

enzotib

477415

477415

add a comment | 

add a comment | 

1 Answer
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up vote
4
down vote

ReleaseHold[Flatten[MapAt[Hold, lis, Position[lis, _List?VectorQ]]]]

a, b, d, f, c, k, h, l, e, a

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
  – Carl Woll
  3 mins ago
  

  
  
  
  

add a comment | 

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1 Answer
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active

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votes

1 Answer
1

active

oldest

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active

oldest

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active

oldest

votes

up vote
4
down vote

ReleaseHold[Flatten[MapAt[Hold, lis, Position[lis, _List?VectorQ]]]]

a, b, d, f, c, k, h, l, e, a

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
  – Carl Woll
  3 mins ago
  

  
  
  
  

add a comment | 

up vote
4
down vote

ReleaseHold[Flatten[MapAt[Hold, lis, Position[lis, _List?VectorQ]]]]

a, b, d, f, c, k, h, l, e, a

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
  – Carl Woll
  3 mins ago
  

  
  
  
  

add a comment | 

up vote
4
down vote

up vote
4
down vote

ReleaseHold[Flatten[MapAt[Hold, lis, Position[lis, _List?VectorQ]]]]

a, b, d, f, c, k, h, l, e, a

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

ReleaseHold[Flatten[MapAt[Hold, lis, Position[lis, _List?VectorQ]]]]

a, b, d, f, c, k, h, l, e, a

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

share|improve this answer

share|improve this answer

answered 31 mins ago

Coolwater

13.5k32150

answered 31 mins ago

Coolwater

13.5k32150

answered 31 mins ago

Coolwater

13.5k32150

13.5k32150

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
  – Carl Woll
  3 mins ago
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
  – Carl Woll
  3 mins ago
  

  
  
  
  

1

1

Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
– Carl Woll
3 mins ago

Another variant is ReleaseHold @ Flatten @ Replace[lis, l_List :> Hold[l], -2]
– Carl Woll
3 mins ago

add a comment | 

 

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