Help with routines choosing unrepeated data from an array

[cubragol]

Hi thanks for running these boards.
I am stuck trying to write a routine in a larger programme.
I want to choose data randomly from an array and write it to a new array. It doesn't matter which order it arrives in as long as data is not repeated in the new array.
I am not using days of the week but have chosen them as an example to hopefully make things clearer
The routine below allows repetition e.g. friday, monday, friday
How do i code it so that three unrepeated pieces of data will be chosen?
I have tried various ways with subroutines but keep coming unstuck.
Can anyone help?
Thanks in advance.

CLS
CLEAR
RANDOMIZE TIMER

DIM weekday$(7)
FOR a = 1 TO 7
READ weekday$(a)
NEXT a

DIM newlist$(3)

FOR z = 1 TO 3
pickday = INT(RND * 7) + 1
newlist$(z) = weekday$(pickday)
NEXT z

FOR a = 1 TO 3
PRINT newlist$(a)
NEXT a

DATA "monday","tuesday", "wednesday", "thursday","friday","saturday","sunday"

[cubragol]

rather inelegant solution probably but here it is

dayprogram:CLS
CLEAR
RANDOMIZE TIMER

DIM weekday$(7)
FOR a = 1 TO 7
READ weekday$(a)
NEXT a

DIM newlist$(3)


DO WHILE z < 3
days:
GOSUB daypick
GOSUB daycheck
IF flag = 1 THEN GOTO days
IF flag = 0 THEN newlist$(z) = tempday$: z = z + 1
LOOP
FOR a = 0 TO 2
PRINT newlist$(a)
NEXT a

DATA "monday","tuesday", "wednesday", "thursday","friday","saturday","sunday"

INPUT ; a$
IF a$ = "y" THEN GOTO dayprogram
STOP

daypick:
pickday = INT(RND * 7) + 1
tempday$ = weekday$(pickday)
RETURN

daycheck:
flag = 0
FOR x = 0 TO z
IF newlist$(x) = tempday$ THEN flag = 1
NEXT x
RETURN

[burger2227]

You don't need to take the values out of the original array. Just make sure the array elements are not in the same order. SWAP allows you to work with 2 different arrays at the same time by trading the values.

Code: Select all

DIM Index(7), weekday$(7)
RANDOMIZE TIMER
CLS
FOR a = 1 TO 7  'set days and index numbers in order
  Index(a) = a
  READ weekday$(a)
NEXT a

FOR i = 1 TO 7
  IF Index(i) = i THEN   'find elements same as index
    DO: j = INT(RND * 7) + 1: LOOP WHILE j = i   'loop until j is not = to  i
    SWAP Index(i), Index(j)   'swap 2 elements
    SWAP weekday$(i), weekday$(j)
  END IF
NEXT

FOR a = 1 TO 7  'check the order
  PRINT weekday$(a)
NEXT


DATA "Monday","Tuesday", "Wednesday", "Thursday","Friday","Saturday","Sunday"

The secret is to SWAP both arrays exactly the same way. I have used this type of procedure to arrange the alphabet so that no letter matches the ASCII code for an anagram puzzle program.

Ted

[cubragol]

Thanks Ted I knew there must be a more elegant way.
I am so rusty.
I learned to program on a Sinclair ZX spectrum and I don't remember having access to the swap command!
Thanks again.

[burger2227]

Your welcome and I have no idea what a Spectrum is LOL!

The big advantage of doing SWAP is that you CAN'T lose anything already in the array. Well, at least it's harder to lose them lol.

Ted