Constructing a string with several index requirements

Hello, I have a vector of numbers r2 that I need to send over a communciation to an array (called ScanArray). The comms is such that I can only send upto 50 elements in each send (Im using writeline)

Heres the 1st 8 values I need to send

r2 =

0    30    60    90   120   150   180   210

and heres my string that I construct that I send with writeline function

command=['ScanArray(0)(0)=',num2str(r2(1,1)),'ScanArray(0)(1)=',num2str(r2(1,2)),'ScanArray(0)(2)=',num2str(r2(1,3)),'ScanArray(0)(3)=',num2str(r2(1,4))]

Rather than write this out for 50 elements ScanArray(0)(0) -> ScanArray(0)(49), is there a more effcient way to construct this. This was my attemp:

           command=[];
            for i=1:50
                 commandnew=['ScanArray(0)(',num2str(i),')=',num2str(r2(1,i))]
                 command=[command,commandnew]
            end  

[Stephen23]

"is there a more effcient way to construct this."

Do not fight MATLAB with loops. Use e.g. strings or COMPOSE:

r2 = 0:30:210;
ix = 1:numel(r2);
tx = "ScanArray(0)(" + ix(:) + ")=" + r2(:)

tx = 8x1 string array
    "ScanArray(0)(1)=0"
    "ScanArray(0)(2)=30"
    "ScanArray(0)(3)=60"
    "ScanArray(0)(4)=90"
    "ScanArray(0)(5)=120"
    "ScanArray(0)(6)=150"
    "ScanArray(0)(7)=180"
    "ScanArray(0)(8)=210"

tx = compose('ScanArray(0)(%u) = %u',ix(:),r2(:))

tx = 8x1 cell array
    {'ScanArray(0)(1) = 0'  }
    {'ScanArray(0)(2) = 30' }
    {'ScanArray(0)(3) = 60' }
    {'ScanArray(0)(4) = 90' }
    {'ScanArray(0)(5) = 120'}
    {'ScanArray(0)(6) = 150'}
    {'ScanArray(0)(7) = 180'}
    {'ScanArray(0)(8) = 210'}

[Voss]

r2 = 0:30:210;
ix = 0:numel(r2)-1;
tx = "ScanArray(0)(" + ix(:) + ")=" + r2(:);
tx = [tx{:}]

tx = 'ScanArray(0)(0)=0ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90ScanArray(0)(4)=120ScanArray(0)(5)=150ScanArray(0)(6)=180ScanArray(0)(7)=210'

tx = compose('ScanArray(0)(%u)=%u',ix(:),r2(:));
tx = [tx{:}]

tx = 'ScanArray(0)(0)=0ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90ScanArray(0)(4)=120ScanArray(0)(5)=150ScanArray(0)(6)=180ScanArray(0)(7)=210'

Answer 1

[Star Strider]

I’m not certain what you need, however this is one option —

r2 = [0    30    60    90   120   150   180   210];

command=['ScanArray(0)(0)=',num2str(r2(1,1)),'ScanArray(0)(1)=',num2str(r2(1,2)),'ScanArray(0)(2)=',num2str(r2(1,3)),'ScanArray(0)(3)=',num2str(r2(1,4))]

command = 'ScanArray(0)(0)=0ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90'

for k = 1:numel(r2)-3
    command = ["ScanArray(0)("+(k-1)+")="+r2(1,k)+"ScanArray(0)("+k+")="+r2(1,k+1)+"ScanArray(0)("+(k+1)+")="+r2(1,k+2)+"ScanArray(0)("+(k+2)+")="+r2(1,k+3)]
end

command = "ScanArray(0)(0)=0ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90"

command = "ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90ScanArray(0)(4)=120"

command = "ScanArray(0)(2)=60ScanArray(0)(3)=90ScanArray(0)(4)=120ScanArray(0)(5)=150"

command = "ScanArray(0)(3)=90ScanArray(0)(4)=120ScanArray(0)(5)=150ScanArray(0)(6)=180"

command = "ScanArray(0)(4)=120ScanArray(0)(5)=150ScanArray(0)(6)=180ScanArray(0)(7)=210"

It may be necessary to expand on that, perhaps with a nested loop, for a multi-row ‘r2’.

.

[Voss]

The square brackets are unnecessary when using string concatenation:

"S"+1

ans = "S1"

["S"+1]

ans = "S1"

Answer 2

[Voss]

r2 = [0 30 60 90 120 150 180 210];

command = sprintf('ScanArray(0)(%d)=%g',[0:numel(r2)-1; r2])

command = 'ScanArray(0)(0)=0ScanArray(0)(1)=30ScanArray(0)(2)=60ScanArray(0)(3)=90ScanArray(0)(4)=120ScanArray(0)(5)=150ScanArray(0)(6)=180ScanArray(0)(7)=210'

The %g is to handle cases where elements of r2 are not integers. If they are always integers you can use %d there instead.

And I don't know but you may need a delimiter between adjacent ScanArray(0) assignments, as in

command = sprintf('ScanArray(0)(%d)=%g ',[0:numel(r2)-1; r2])

command = 'ScanArray(0)(0)=0 ScanArray(0)(1)=30 ScanArray(0)(2)=60 ScanArray(0)(3)=90 ScanArray(0)(4)=120 ScanArray(0)(5)=150 ScanArray(0)(6)=180 ScanArray(0)(7)=210 '

or

command = sprintf('ScanArray(0)(%d)=%g;',[0:numel(r2)-1; r2])

command = 'ScanArray(0)(0)=0;ScanArray(0)(1)=30;ScanArray(0)(2)=60;ScanArray(0)(3)=90;ScanArray(0)(4)=120;ScanArray(0)(5)=150;ScanArray(0)(6)=180;ScanArray(0)(7)=210;'

etc.

Answer 3

[Steven Lord]

r2 = [0    30    60    90   120   150   180   210];
ind = 0:numel(r2)-1;
result = join("ScanArray(0)(" + ind + ")=" + r2, newline)

result = 
    "ScanArray(0)(0)=0
     ScanArray(0)(1)=30
     ScanArray(0)(2)=60
     ScanArray(0)(3)=90
     ScanArray(0)(4)=120
     ScanArray(0)(5)=150
     ScanArray(0)(6)=180
     ScanArray(0)(7)=210"

Replace newline with ";" to join the substrings with semicolons rather than newlines (which I used so you can easily see the individual substrings included in result.)

[Jason]

Thanks Steven (and everyone else, quite a few nice ways)

i've just realised I need to change my request slightly, what now if I wanted the output to have the 2nd argument in the array index to vary only from 0 to 3 and then increment the 1st index. Upto 48 total elements

The values should still equate to the 1D vector (R1) values:

r2 = [0    30    60    90   120   150   180   210 ....   500];

result = 
"ScanArray(0)(0)=0
ScanArray(0)(1)=30 
ScanArray(0)(2)=60 
ScanArray(0)(3)=90
ScanArray(1)(1)=120 
ScanArray(1)(2)=150 
ScanArray(1)(3)=180 
ScanArray(1)(4)=210
……
ScanArray(3)(4)=500 "

I basically want to populate my array in this order:

I do have to go upto column number 9399, but I need to send the data in chuncks of 50 or less, so 48 in this case. After the 1st 48 elements being filled, R1 will reset so will need to reset its index.

Thanks

Jason

[Voss]

r2 = (0:47)*30;

N = numel(r2);
n = 4;
assert(mod(N,n) == 0)

[idx1,idx2] = meshgrid(0:N/n-1,0:n-1)

idx1 = 4×12

0 1 2 3 4 5 6 7 8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11 0 1 2 3 4 5 6 7 8 9 10 11

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idx2 = 4×12

0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3

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result = join("ScanArray("+idx1(:)+")("+idx2(:)+")="+r2(:),newline())

result = 
    "ScanArray(0)(0)=0
     ScanArray(0)(1)=30
     ScanArray(0)(2)=60
     ScanArray(0)(3)=90
     ScanArray(1)(0)=120
     ScanArray(1)(1)=150
     ScanArray(1)(2)=180
     ScanArray(1)(3)=210
     ScanArray(2)(0)=240
     ScanArray(2)(1)=270
     ScanArray(2)(2)=300
     ScanArray(2)(3)=330
     ScanArray(3)(0)=360
     ScanArray(3)(1)=390
     ScanArray(3)(2)=420
     ScanArray(3)(3)=450
     ScanArray(4)(0)=480
     ScanArray(4)(1)=510
     ScanArray(4)(2)=540
     ScanArray(4)(3)=570
     ScanArray(5)(0)=600
     ScanArray(5)(1)=630
     ScanArray(5)(2)=660
     ScanArray(5)(3)=690
     ScanArray(6)(0)=720
     ScanArray(6)(1)=750
     ScanArray(6)(2)=780
     ScanArray(6)(3)=810
     ScanArray(7)(0)=840
     ScanArray(7)(1)=870
     ScanArray(7)(2)=900
     ScanArray(7)(3)=930
     ScanArray(8)(0)=960
     ScanArray(8)(1)=990
     ScanArray(8)(2)=1020
     ScanArray(8)(3)=1050
     ScanArray(9)(0)=1080
     ScanArray(9)(1)=1110
     ScanArray(9)(2)=1140
     ScanArray(9)(3)=1170
     ScanArray(10)(0)=1200
     ScanArray(10)(1)=1230
     ScanArray(10)(2)=1260
     ScanArray(10)(3)=1290
     ScanArray(11)(0)=1320
     ScanArray(11)(1)=1350
     ScanArray(11)(2)=1380
     ScanArray(11)(3)=1410"

[Voss]

Or:

r2 = (0:47)*30;

N = numel(r2);
n = 4;
assert(mod(N,n) == 0)

result = strjoin("ScanArray("+(0:N/n-1)+")("+(0:n-1).'+")="+reshape(r2,n,[]),newline())

result = 
    "ScanArray(0)(0)=0
     ScanArray(0)(1)=30
     ScanArray(0)(2)=60
     ScanArray(0)(3)=90
     ScanArray(1)(0)=120
     ScanArray(1)(1)=150
     ScanArray(1)(2)=180
     ScanArray(1)(3)=210
     ScanArray(2)(0)=240
     ScanArray(2)(1)=270
     ScanArray(2)(2)=300
     ScanArray(2)(3)=330
     ScanArray(3)(0)=360
     ScanArray(3)(1)=390
     ScanArray(3)(2)=420
     ScanArray(3)(3)=450
     ScanArray(4)(0)=480
     ScanArray(4)(1)=510
     ScanArray(4)(2)=540
     ScanArray(4)(3)=570
     ScanArray(5)(0)=600
     ScanArray(5)(1)=630
     ScanArray(5)(2)=660
     ScanArray(5)(3)=690
     ScanArray(6)(0)=720
     ScanArray(6)(1)=750
     ScanArray(6)(2)=780
     ScanArray(6)(3)=810
     ScanArray(7)(0)=840
     ScanArray(7)(1)=870
     ScanArray(7)(2)=900
     ScanArray(7)(3)=930
     ScanArray(8)(0)=960
     ScanArray(8)(1)=990
     ScanArray(8)(2)=1020
     ScanArray(8)(3)=1050
     ScanArray(9)(0)=1080
     ScanArray(9)(1)=1110
     ScanArray(9)(2)=1140
     ScanArray(9)(3)=1170
     ScanArray(10)(0)=1200
     ScanArray(10)(1)=1230
     ScanArray(10)(2)=1260
     ScanArray(10)(3)=1290
     ScanArray(11)(0)=1320
     ScanArray(11)(1)=1350
     ScanArray(11)(2)=1380
     ScanArray(11)(3)=1410"

[Jason]

Thankyou!

Answer 4

[Jason]

Could i ask how I would make the double for loop work using idexing:

I start with this:

jx=1:4;
ix=0:3
tx = "ScanArray(0)(" + ix(:) + ")=" 

This correctly gives me this:

tx = 

4×1 string array

"ScanArray(0)(0)="
"ScanArray(0)(1)="
"ScanArray(0)(2)="
"ScanArray(0)(3)="

Now I want the first index to increment also by the jx term (still loop the 2nd index 0,1,2,3)

I tried this:

tx(jx) = "ScanArray("+jx(:)-1+")(" + ix(:) + ")="  

[Star Strider]

Thst should work essentially as you wrote it.

The only change I made here is to enclose the arithmetic operation in parentheses —

jx = 1:4

jx = 1×4

1 2 3 4

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ix = 0:3

ix = 1×4

0 1 2 3

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tx(jx,:) = "ScanArray("+(jx(:)-1)+")(" + ix(:) + ")="  

tx = 4x1 string array
    "ScanArray(0)(0)="
    "ScanArray(1)(1)="
    "ScanArray(2)(2)="
    "ScanArray(3)(3)="

.

[Jason]

thanks, but I need

ScanArray(0)(0)=

ScanArray(0)(1)=

ScanArray(0)(2)=

ScanArray(0)(3)=

ScanArray(1)(0)=

ScanArray(1)(1)=

ScanArray(1)(2)=

ScanArray(1)(3)=

ScanArray(2)(0)=

ScanArray(2)(1)=

etc

[Stephen23]

jx = 1:4;
ix = 0:3;
tx = "ScanArray("+(jx-1)+")("+ix(:)+")=";
tx = tx(:)

tx = 16x1 string array
    "ScanArray(0)(0)="
    "ScanArray(0)(1)="
    "ScanArray(0)(2)="
    "ScanArray(0)(3)="
    "ScanArray(1)(0)="
    "ScanArray(1)(1)="
    "ScanArray(1)(2)="
    "ScanArray(1)(3)="
    "ScanArray(2)(0)="
    "ScanArray(2)(1)="
    "ScanArray(2)(2)="
    "ScanArray(2)(3)="
    "ScanArray(3)(0)="
    "ScanArray(3)(1)="
    "ScanArray(3)(2)="
    "ScanArray(3)(3)="

[Jason]

Thankyou!