My code is like below:
I have actually two Questions regarding my code:
1:From this code i want to find the value of D.Even I get the value of "D" but every time current "D" add up with previous "D". Like get
D(1,:)=30 30 30 30 30
D(2,:)=60 60 60 60 60
D(3,:)=89 89 89 90 90
But i want to get
D(1,:)=30 30 30 30 30
D(2,:)=30 30 30 30 30
D(3,:)=29 29 29 30 30
I know i can do this by extracting the current D from the previous D after getting the for loop but i do not want to do this.I want to do something within the for loop.
Another question is i need to run this code for iteration=100 times and i need to store the value of "D" for every trial in a cell array, because later i need to use those values of D.
Matlab experts need your help and suggestion for two questions.
First part: after the loop do this
D = [D(1,:), diff(D)];
e.g.
D = [30 30 30 30 30
60 60 60 60 60
89 89 89 90 90];
[D(1,:); diff(D)]
ans =
30 30 30 30 30
30 30 30 30 30
29 29 29 30 30
Second part: why just store it in a new matrix?
AllTheDs{counter} = D %// This will be outside your current for-loop but presumably inside your new loop that counts to 20k
My first thought was also the diff solution as proposed by #Dan. However then I started wondering whether the problem was perhaps that you just keep adding things without the intention to do so.
I see you have this as the only line where rec2_Wopt is updated
rec2_Wopt(1) = rec2_Wopt(1) + sum(RecP) ;
Hence it is logical that after the second loop, it will include the additions of the first loop and the second loop.
To solve this, start each loop by resetting your variables. For this variable it would be:
rec2_Wopt(1) = 0
Or
rec2_Wopt = zeros(1, length(N)) ;
Related
I have a function that takes as input some of the values in a table and returns a tuple if you will - three separate return values, which I want to transpose into the output of a query. Here's a simplified example of what I want to achieve:
multiplier:{(x*2;x*3;x*3)};
select twoX:multiplier[price][0]; threeX:multiplier[price][1]; fourX:multiplier[price][2] from data;
The above basically works (I think I've got the syntax right for the simplified example - if not then hopefully my intention is clear), but is inefficient because I'm calling the function three times and throwing away most of the output each time. I want to rewrite the query to only call the function once, and I'm struggling.
Update
I think I missed a crucial piece of information in my explanation of the problem which affects the outcome - I need to get other data in the query alongside the output of my function. Here's a hopefully more realistic example:
multiplier:{(x*2;x*3;x*4)};
select average:avg price, total:sum price, twoX:multiplier[sum price][0]; threeX:multiplier[sum price][1]; fourX:multiplier[sum price][2] by category from data;
I'll have a go at adapting your answers to fit this requirement anyway, and apologies for missing this bit of information. The real function if a proprietary and fairly complex algorithm and the real query has about 30 output columns, hence the attempt at simplifying the example :)
If you're just looking for the results themselves you can extract (exec) as lists, create dictionary and then flip the dictionary into a table:
q)exec flip`twoX`threeX`fourX!multiplier[price] from ([]price:til 10)
twoX threeX fourX
-----------------
0 0 0
2 3 4
4 6 8
6 9 12
8 12 16
10 15 20
12 18 24
14 21 28
16 24 32
18 27 36
If you need other columns from the original table too then its trickier but you could join the tables sideways using ,'
q)t:([]price:til 10)
q)t,'exec flip`twoX`threeX`fourX!multiplier[price] from t
An apply # can also achieve what you want. Here data is just a table with 10 random prices. # is then used to apply the multiplier function to the price column while also assigning a column name to each of the three resulting lists:
q)data:([] price:10?100)
q)multiplier:{(x*2;x*3;x*3)}
q)#[data;`twoX`threeX`fourX;:;multiplier data`price]
price twoX threeX fourX
-----------------------
80 160 240 240
24 48 72 72
41 82 123 123
0 0 0 0
81 162 243 243
10 20 30 30
36 72 108 108
36 72 108 108
16 32 48 48
17 34 51 51
for a=1:50; %numbers 1 through 50
for b=1:50;
c=sqrt(a^2+b^2);
if c<=50&c(rem(c,1)==0);%if display only if c<=50 and c=c/1 has remainder of 0
pyth=[a,b,c];%pythagorean matrix
disp(pyth)
else c(rem(c,1)~=0);%if remainder doesn't equal to 0, omit output
end
end
end
answer=
3 4 5
4 3 5
5 12 13
6 8 10
7 24 25
8 6 10
8 15 17
9 12 15
9 40 41
10 24 26
12 5 13
12 9 15
12 16 20
12 35 37
14 48 50
15 8 17
15 20 25
15 36 39
16 12 20
16 30 34
18 24 30
20 15 25
20 21 29
21 20 29
21 28 35
24 7 25
24 10 26
24 18 30
24 32 40
27 36 45
28 21 35
30 16 34
30 40 50
32 24 40
35 12 37
36 15 39
36 27 45
40 9 41
40 30 50
48 14 50
This problem involves the Pythagorean theorem but we cannot use the built in function so I had to write one myself. The problem is for example columns 1 & 2 from the first two rows have the same numbers. How do I code it so it only deletes one of the rows if the columns 1 and 2 have the same number combination? I've tried unique function but it doesn't really delete the combinations. I have read about deleting duplicates from previous posts but those have confused me even more. Any help on how to go about this problem will help me immensely!
Thank you
welcome to StackOverflow.
The problem in your code seems to be, that pyth only contains 3 values, [a, b, c]. The unique() funcion used in the next line has no effect in that case, because only one row is contained in pyth. another issue is, that the values idx and out are calculated in each loop cycle. This should be placed after the loops. An example code could look like this:
pyth = zeros(0,3);
for a=1:50
for b=1:50
c = sqrt(a^2 + b^2);
if c<=50 && rem(c,1)==0
abc_sorted = sort([a,b,c]);
pyth = [pyth; abc_sorted];
end
end
end
% do final sorting outside of the loop
[~,idx] = unique(pyth, 'rows', 'stable');
out = pyth(idx,:);
disp(out)
a few other tips for writing MATLAB code:
You do not need to end for or if/else stements with a semicolon
else statements cover any other case not included before, so they do not need a condition.
Some performance reommendations:
Due to the symmetry of a and b (a^2 + b^2 = b^2 + a^2) the b loop could be constrained to for b=1:a, which would roughly save you half of the loop cycles.
if you use && for contencation of scalar values, the second part is not evaluated, if the first part already fails (source).
Regards,
Chris
You can also linearize your algorithm (but we're still using bruteforce):
[X,Y] = meshgrid(1:50,1:50); %generate all the combination
C = (X(:).^2+Y(:).^2).^0.5; %sums of two square for every combination
ind = find(rem(C,1)==0 & C<=50); %get the index
res = unique([sort([X(ind),Y(ind)],2),C(ind)],'rows'); %check for uniqueness
Now you could really optimized your algorithm using math, you should read this question. It will be useful if n>>50.
There are three columns, date, x, y
I need to calculate the running sum/total of y for a specific date (today's date more specifically). The data is in two datasources and looks like this in first data source.
DATE X Z
5-Sep
6-Sep 26 101
7-Sep 27 100
8-Sep 28 99
9-Sep 29 98
10-Sep 30 98
11-Sep 30 98
12-Sep 30 97
13-Sep 31 96
14-Sep 32 95
15-Sep 33 94
16-Sep 34 93
17-Sep 35 92
18-Sep 35 92
and like this is second data source
DATE Y
5-Sep 166
6-Sep 182
7-Sep 130
8-Sep 93
9-Sep 107
10-Sep 95
11-Sep 128
12-Sep 173
13-Sep 154
14-Sep 136
15-Sep 79
16-Sep 61
17-Sep 156
18-Sep 66
Lets say that today's date is 17th Sep, then I need to calculate the running sum of 'Z' until today and display it next to the 'X' column. Something like this
17-Sep 35 1499.
How do I do that?
(I tried using sets with date by limiting the date to today but then the running sum doesn't work, also there are some errors in calculated field which is because the data is in two different sources)
Please ask if need more clarification
Using the Super store data, I created a date parameter. Then created a calculated field as follows:
if [date param] >= [Order Date] then [Sales] end
Now this will display sales prior to your selected date parameter. I also created a filter calc to only see data prior to the selected date in the param.
[date param]>=[Order Date]
Place this in the filter shelf and select True.
Now place date field on Rows and your sales calculated field on Text pill. Right click on it and select Quick Table Calculation > Running Total.
See sample workbook here: https://www.dropbox.com/s/p42tx86v4qidlvn/170327%20stack%20question.twbx?dl=0
EDIT:
If you just want to see the total and the date selected, create a calc field for "last" as last() then filter that for zero.
In my research, I have to identify row and column which has same value in matrix.
here for example the form of matrix:
A= [60 27 45 72 22 14 56 2 8 39 18 12;
72 27 60 45 11 7 3 23 41 17 56 39]
Then, I want to identify row 1 until 4 in column 1 and column 2.
here part of my code.
done =all(ismember(A(1,1:4),A(2,1:4))); %Code that I want to ask you.
Please Look at in row 1-4 and column 1-4;
if I use above code, done will always give true (1). but it is not my desire, because A(1,1) is not same with A(2,1), then A(1,3) is also not same with A(2,3), A(1,4) is also not same with A(2,4).
If you want to check whether the values in A(1,1:4) are the same as in A(2,1:4) you could just use
done =all(A(1,1:4) == A(2,1:4));
Quick MATLAB question.
What would be the best/most efficient way to select a certain number of elements, 'n' in windows of 'm'. In other words, I want to select the first 50 elements of a sequence, then elements 10-60, then elements 20-70 ect.
Right now, my sequence is in vector format(but this can easily be changed).
EDIT:
The sequences that I am dealing with are too long to be stored in my RAM. I need to be able to create the windows, and then call upon the window that I want to analyze/preform another command on.
Do you have enough RAM to store a 50-by-nWindow array in memory? In that case, you can generate your windows in one go, and then apply your processing on each column
%# idxMatrix has 1:50 in first col, 11:60 in second col etc
idxMatrix = bsxfun(#plus,(1:50)',0:10:length(yourVector)-50); %'#
%# reshapedData is a 50-by-numberOfWindows array
reshapedData = yourVector(idxMatrix);
%# now you can do processing on each column, e.g.
maximumOfEachWindow = max(reshapedData,[],1);
To complement Kerrek's answer: if you want to do it in a loop, you can use something like
n = 50
m = 10;
for i=1:m:length(v)
w = v(i:i+n);
% Do something with w
end
There's a slight issue with the description of your problem. You say that you want "to select the first 50 elements of a sequence, then elements 10-60..."; however, this would translate to selecting elements:
1-50
10-60
20-70
etc.
That first sequence should be 0-10 to fit the pattern which of course in MATLAB would not make sense since arrays use one-indexing. To address this, the algorithm below uses a variable called startIndex to indicate which element to start the sequence sampling from.
You could accomplish this in a vectorized way by constructing an index array. Create a vector consisting of the starting indices of each sequence. For reuse sake, I put the length of the sequence, the step size between sequence starts, and the start of the last sequence as variables. In the example you describe, the length of the sequence should be 50, the step size should be 10 and the start of the last sequence depends on the size of the input data and your needs.
>> startIndex = 10;
>> sequenceSize = 5;
>> finalSequenceStart = 20;
Create some sample data:
>> sampleData = randi(100, 1, 28)
sampleData =
Columns 1 through 18
8 53 10 82 82 73 15 66 52 98 65 81 46 44 83 9 14 18
Columns 19 through 28
40 84 81 7 40 53 42 66 63 30
Create a vector of the start indices of the sequences:
>> sequenceStart = startIndex:sequenceSize:finalSequenceStart
sequenceStart =
10 15 20
Create an array of indices to index into the data array:
>> index = cumsum(ones(sequenceSize, length(sequenceStart)))
index =
1 1 1
2 2 2
3 3 3
4 4 4
5 5 5
>> index = index + repmat(sequenceStart, sequenceSize, 1) - 1
index =
10 15 20
11 16 21
12 17 22
13 18 23
14 19 24
Finally, use this index array to reference the data array:
>> sampleData(index)
ans =
98 83 84
65 9 81
81 14 7
46 18 40
44 40 53
Use (start : step : end) indexing: v(1:1:50), v(10:1:60), etc. If the step is 1, you can omit it: v(1:50).
Consider the following vectorized code:
x = 1:100; %# an example sequence of numbers
nwind = 50; %# window size
noverlap = 40; %# number of overlapping elements
nx = length(x); %# length of sequence
ncol = fix((nx-noverlap)/(nwind-noverlap)); %# number of sliding windows
colindex = 1 + (0:(ncol-1))*(nwind-noverlap); %# starting index of each
%# indices to put sequence into columns with the proper offset
idx = bsxfun(#plus, (1:nwind)', colindex)-1; %'
%# apply the indices on the sequence
slidingWindows = x(idx)
The result (truncated for brevity):
slidingWindows =
1 11 21 31 41 51
2 12 22 32 42 52
3 13 23 33 43 53
...
48 58 68 78 88 98
49 59 69 79 89 99
50 60 70 80 90 100
In fact, the code was adapted from the now deprecated SPECGRAM function from the Signal Processing Toolbox (just do edit specgram.m to see the code).
I omitted parts that zero-pad the sequence in case the sliding windows do not evenly divide the entire sequence (for example x=1:105), but you can easily add them again if you need that functionality...