APALINDROME

Xlambda · Apr 4, 2021

APALINDROME checks an array for palindromes. calls AKEEP , AREVERSE

Excel Formula:

=LAMBDA(a,
    LET(x,AKEEP(a,T_CHARS(,2,),),y,AREVERSE(x),
       IF(x=y,"Yes !","No !")
    )
)

LAMBDA 7.0.xlsx

A

B

C

D

E

1

check palindrome sentences

=APALINDROME(A2:A6)

2

¡ Murder for a jar of red rum !

Yes !

3

Borrow or rob?

Yes !

4

Eva, can I see bees in a cave?

Yes !

5

Yo, banana boy!

Yes !

6

Radar is radar !

No !

7

APALINDROME post

Cell Formulas
Range	Formula
C1	C1	=FORMULATEXT(C2)
C2:C6	C2	=APALINDROME(A2:A6)
Dynamic array formulas.

schardt679 · Apr 5, 2021

How do you do this? Everytime I think of something, I check here minutes later you post the exact LAMBDA. I was just thinking of a PALINDROME LAMBDA. Great work

Xlambda · Apr 11, 2021

Hi, thanks, does not matter, if you have a different approach you should post. Only time, and other users will tell which one will get traction.
On 98% of the cases when I write a formula, I am stuck to the first idea that comes to my mind, and this could make me blind to other better solutions, solutions that other eyes can see, and so on.
So, I encourage you to post, you are a very good exceler. ✌?

lrobbo314 · Jan 20, 2023

I've been playing around with making recursive functions.

Came up with a way to do a PALINDROME function recursively.

PALINDROME

Excel Formula:

=LAMBDA(
    text,
        IF(
            AOR(LEN(text),"0,1"),
                TRUE,
                IF(
                    LEFT(text)=RIGHT(text),
                        PALINDROME(MID(text,2,LEN(text)-2)),
                        FALSE
                )
            )
)

PALINDROME

J

K

21

racecar

TRUE

22

abba

TRUE

23

monkey

FALSE

Sheet5

Cell Formulas
Range	Formula
K21:K23	K21	=PALINDROME(J21)

Helper function AOR, checks to see if any value in comma separated string is equal to value.

AOR

Excel Formula:

=LAMBDA(
    val,oStr,
        LET(
            ts,TEXTSPLIT(oStr,","),
            OR(
                MAP(
                    ts,
                    LAMBDA(
                        x,
                        IFERROR(
                            x+0=val,
                            x=val
                        )
                    )
                )
            )
        )
)

Xlambda · Jan 23, 2023

Cool that you play with recursive functions !!

In this case, my function was designed to work not only with single words in single cells, but with an array vector of sentences with random punctuation marks.
Anyhow, if I would have designed it for single words only palindrome check, I would have used one of these 2:
ISPLNDRM(x) - non recursive

Excel Formula:

=LAMBDA(x,LET(l,LEN(x),s,SEQUENCE(l),AND(MID(x,s,1)=MID(x,l-s+1,1))))

PLNDRM(x) - recursive (does not call any helper function)

Excel Formula:

=LAMBDA(x,LET(l,LEN(x),IF(l<2,TRUE,IF(LEFT(x,1)=RIGHT(x,1),PLNDRM(MID(x,2,l-2)),FALSE))))

Book1.xlsx

A

B

C

D

E

F

G

H

I

J

K

L

1

Wrong results for sentences

2

lrobbo314's fction

3

¡ Murder for a jar of red rum !

FALSE

=PALINDROME(A3)

4

Borrow or rob?

FALSE

=PALINDROME(A4)

5

Eva, can I see bees in a cave?

FALSE

=PALINDROME(A5)

6

Yo, banana boy!

FALSE

=PALINDROME(A6)

7

8

Single cells, single words

9

non recursive

recursive

10

11

aba

12

abba

TRUE

=ISPLNDRM(A12)

TRUE

=PLNDRM(A12)

13

racecar

TRUE

=ISPLNDRM(A13)

TRUE

=PLNDRM(A13)

14

A12321A

TRUE

=ISPLNDRM(A14)

TRUE

=PLNDRM(A14)

15

xyzyx

TRUE

=ISPLNDRM(A15)

TRUE

=PLNDRM(A15)

16

Level

TRUE

=ISPLNDRM(A16)

TRUE

=PLNDRM(A16)

17

Civic

TRUE

=ISPLNDRM(A17)

TRUE

=PLNDRM(A17)

18

Kayak

TRUE

=ISPLNDRM(A18)

TRUE

=PLNDRM(A18)

19

nopalindrome

FALSE

=ISPLNDRM(A19)

FALSE

=PLNDRM(A19)

20

21

ISPLNDRM(x) =

22

=LAMBDA(x,LET(l,LEN(x),s,SEQUENCE(l),AND(MID(x,s,1)=MID(x,l-s+1,1))))

23

24

PLNDRM(x) =

25

=LAMBDA(x,LET(l,LEN(x),IF(l<2,TRUE,IF(LEFT(x,1)=RIGHT(x,1),PLNDRM(MID(x,2,l-2)),FALSE))))

26

Sheet1

Cell Formulas
Range	Formula
C3:C6	C3	=FORMULATEXT(B3:B6)
B3:B6	B3	=PALINDROME(A3)
C11:C19,F11:F19	C11	=FORMULATEXT(B11:B19)
B11:B19	B11	=ISPLNDRM(A11)
E11:E19	E11	=PLNDRM(A11)
Dynamic array formulas.

lrobbo314 · Jan 25, 2023

Here is another way that I came up with.

Also, just for fun, I asked ChatGPT to write a palindrome function. It failed 3 times before reverting to VBA. The VBA was a 1-liner and it worked. But, I think we're safe from GPT for a while.

XPALINDROME

Excel Formula:

=LAMBDA(range,
    MAP(range,
        LAMBDA(t,
            LET(n,INT(LEN(t)/2),
            r,REVTEXT(t),
                LEFT(t,n)=LEFT(r,n))
        )
    )
)

REVTEXT

Excel Formula:

=LAMBDA(text,
    LET(n,LEN(text),
        TEXTJOIN("",,MID(text,SEQUENCE(n,,n,-1),1))
    )
)

Xlambda · Jan 30, 2023

Just for fun "comment"

: if XPALINDROME already calls r,REVTEXT(t), I don't think that comparing only half of the string, LEFT(t,n)=LEFT(r,n), will make the formula more efficient than using only t=r

Excel Formula:

=LAMBDA(range,
    MAP(range,
        LAMBDA(t,
            LET(r,REVTEXT(t),
                t=r)
        )
    )
)

lrobbo314 · Jan 30, 2023

I realized that after I posted it, lol. Was kinda hoping you wouldn't notice.

Xlambda · Feb 5, 2023

lrobbo314 said:
I realized that after I posted it, lol. Was kinda hoping you wouldn't notice.

. Lol.
Anyhow, an updated 2023 APLNDRM(ar) function, Array Palindrome: checks an array of sentences for palindromes. Does not call any other function.

Excel Formula:

=LAMBDA(ar,
    LET(
        a, CONCAT(REDUCE(UPPER(ar), CHAR(SEQUENCE(26, , 65)), LAMBDA(v, i, SUBSTITUTE(v, i, "")))),
        r, REDUCE(ar, UNIQUE(MID(a, SEQUENCE(LEN(a)), 1)), LAMBDA(v, i, SUBSTITUTE(v, i, ""))),
        p, LAMBDA(x, LET(l, LEN(x), s, SEQUENCE(l), AND(MID(x, s, 1) = MID(x, l - s + 1, 1)))),
        MAP(r, p)
    )
)

Cool palindrome sentences from: 190+ Fun, Interesting Palindrome Words
Let's check them all.

Book1.xlsx

A

B

C

D

E

F

G

H

1

2

=TEXTSPLIT(A3,,CHAR(10))

=APLNDRM(C3#)

3

Dammit, I’m mad! A man, a plan, a canal – Panama. Don’t nod. No lemon, no melon! Bird rib. Go hang a salami, I’m a lasagna hog. Do geese see God? Mr. Owl ate my metal worm. Was it a car or a cat I saw? Borrow or rob? I did, did I? Evil did I dwell; lewd I did live. Rats live on no evil star. My gym. No devil lived on. Ma is a nun, as I am. A nut for a jar of tuna. Yo, banana boy! Red rum, sir, is murder. Madam, in Eden, I’m Adam. Taco cat. Al lets Della call Ed “Stella.” Amore, Roma. As I pee sir, I see Pisa! Dennis sinned. Step on no pets. UFO tofu? But sad Eva saved a stub. No trace; not one carton. No, sir, prefer prison. Do nine men interpret? “Nine men,” I nod. Bombard a drab mob. No “x” in “Nixon”. Ma is as selfless as I am. Gateman sees name, garageman sees name tag. A Toyota. Race fast, safe car. A Toyota. Top spot. Drab as a fool, aloof as a bard. Now I see bees, I won. Was it a cat I saw? Cigar? Toss it in a can. It is so tragic. Never odd or even Evade me, Dave. Race fast, safe car. Flee to me, remote elf. Naomi, did I moan? Ed, I saw Harpo Marx ram Oprah W. aside. Campus Motto: Bottoms up, Mac! Name now one man. Doc, note I dissent: a fast never prevents a fatness. I diet on cod. Rise to vote, sir. Senile felines. Murder for a jar of red rum. Dogma? I am God. Won’t lovers revolt now? Saw tide rose? So red it was. Stack cats. Did I draw Della too tall, Edward? I did? A Santa dog lived as a devil god at NASA. Meet animals; laminate ’em. Oozy rat in a sanitary zoo. So many dynamos! A tin mug for a jar of gum, Nita. Madam I’m Adam. Able was I, ere I saw Elba. Eva, can I see bees in a cave? Lived on Decaf; faced no Devil. Stella won no wallets. Cain: a maniac. Lonely Tylenol. No lemon, no melon.

Dammit, I’m mad!

TRUE

all palindromes?

4

A man, a plan, a canal – Panama.

TRUE

=AND(E3#)

5

Don’t nod.

TRUE

6

No lemon, no melon!

TRUE

7

Bird rib.

TRUE

8

Go hang a salami, I’m a lasagna hog.

TRUE

9

Do geese see God?

TRUE

10

Mr. Owl ate my metal worm.

TRUE

11

Was it a car or a cat I saw?

TRUE

12

Borrow or rob?

TRUE

13

I did, did I?

TRUE

14

Evil did I dwell; lewd I did live.

TRUE

15

Rats live on no evil star.

TRUE

16

My gym.

TRUE

17

No devil lived on.

TRUE

18

Ma is a nun, as I am.

TRUE

19

A nut for a jar of tuna.

TRUE

20

Yo, banana boy!

TRUE

21

Red rum, sir, is murder.

TRUE

22

Madam, in Eden, I’m Adam.

TRUE

23

Taco cat.

TRUE

24

Al lets Della call Ed “Stella.”

TRUE

25

Amore, Roma.

TRUE

26

As I pee sir, I see Pisa!

TRUE

27

Dennis sinned.

TRUE

28

Step on no pets.

TRUE

29

UFO tofu?

TRUE

30

But sad Eva saved a stub.

TRUE

31

No trace; not one carton.

TRUE

32

No, sir, prefer prison.

TRUE

33

Do nine men interpret? “Nine men,” I nod.

TRUE

34

Bombard a drab mob.

TRUE

35

No “x” in “Nixon”.

TRUE

36

Ma is as selfless as I am.

TRUE

37

Gateman sees name, garageman sees name tag.

TRUE

38

A Toyota. Race fast, safe car. A Toyota.

TRUE

39

Top spot.

TRUE

40

Drab as a fool, aloof as a bard.

TRUE

41

Now I see bees, I won.

TRUE

42

Was it a cat I saw?

TRUE

43

Cigar? Toss it in a can. It is so tragic.

TRUE

44

Never odd or even

TRUE

45

Evade me, Dave.

TRUE

46

Race fast, safe car.

TRUE

47

Flee to me, remote elf.

TRUE

48

Naomi, did I moan?

TRUE

49

Ed, I saw Harpo Marx ram Oprah W. aside.

TRUE

50

Campus Motto: Bottoms up, Mac!

TRUE

51

Name now one man.

TRUE

52

Doc, note I dissent: a fast never prevents a fatness. I diet on cod.

TRUE

53

Rise to vote, sir.

TRUE

54

Senile felines.

TRUE

55

Murder for a jar of red rum.

TRUE

56

Dogma? I am God.

TRUE

57

Won’t lovers revolt now?

TRUE

58

Saw tide rose? So red it was.

TRUE

59

Stack cats.

TRUE

60

Did I draw Della too tall, Edward? I did?

TRUE

61

A Santa dog lived as a devil god at NASA.

TRUE

62

Meet animals; laminate ’em.

TRUE

63

Oozy rat in a sanitary zoo.

TRUE

64

So many dynamos!

TRUE

65

A tin mug for a jar of gum, Nita.

TRUE

66

Madam I’m Adam.

TRUE

67

Able was I, ere I saw Elba.

TRUE

68

Eva, can I see bees in a cave?

TRUE

69

Lived on Decaf; faced no Devil.

TRUE

70

Stella won no wallets.

TRUE

71

Cain: a maniac.

TRUE

72

Lonely Tylenol.

TRUE

73

No lemon, no melon.

TRUE

74

Sheet2

Cell Formulas
Range	Formula
E2,G4,C2	E2	=FORMULATEXT(E3)
C3:C73	C3	=TEXTSPLIT(A3,,CHAR(10))
E3:E73	E3	=APLNDRM(C3#)
G5	G5	=AND(E3#)
Dynamic array formulas.

Xlambda · Feb 5, 2023

Book1.xlsx

A

1

The Longest Palindrome Examples

2

3

Are we not pure? “No sir!” Panama’s moody Noriega brags. “It is garbage!” Irony dooms a man; a prisoner up to new era.

4

T. Eliot, top bard, notes putrid tang emanating, is sad. I’d assign it a name: gnat dirt upset on drab pot-toilet.

5

Embargos are macabre. Sad Nell, listen O, not to no nets. I’ll lend a Serb a camera, so grab me.

6

Er, go on, trap Steven in, I say. Me oh my. Nor can an “air” bee sew. We see, Brian. An acronym? Hoe my asinine vet’s part? No, ogre.

7

Are we not pure? “No sir!” Panama’s moody Noriega brags. “It is garbage!” Irony dooms a man; a prisoner up to new era.

8

“Son, say a papaya.” “Papayas.” “No ‘s.'”

9

Dennis, Nell, Edna, Leon, Nedra, Anita, Rolf, Nora, Alice, Carol, Leo, Jane, Reed, Dena, Dale, Basil, Rae, Penny, Lana, Dave, Denny, Lena, Ida, Bernadette, Ben, Ray, Lila, Nina, Jo, Ira, Mara, Sara, Mario, Jan, Ina, Lily, Arne, Bette, Dan, Reba, Diane, Lynn, Ed, Eva, Dana, Lynne, Pearl, Isabel, Ada, Ned, Dee, Rena, Joel, Lora, Cecil, Aaron, Flora, Tina, Arden, Noel, and Ellen sinned.

10

11

=APLNDRM(A3:A9)

12

TRUE

13

TRUE

14

TRUE

15

TRUE

16

TRUE

17

TRUE

18

TRUE

19

Sheet3

Cell Formulas
Range	Formula
A11	A11	=FORMULATEXT(A12)
A12:A18	A12	=APLNDRM(A3:A9)
Dynamic array formulas.

APALINDROME

Xlambda

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schardt679

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Xlambda

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lrobbo314

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Xlambda

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lrobbo314

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Xlambda

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