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# Steven Niggebrugge

### Shell Asset Management Company B.V.

Last seen: 1 year ago Active since 2016

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Question

Building random forest with cross-validation
Hi, i have been wondering for some time now how random forests (Bagging, or AdaBoost, doesn't matter) are built when using cros...

1 year ago | 0 answers | 0

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Question

Convert categorical back to integer
Hi, i convert an integer to a categorical a=[-1 0 1] b=categorical(a) now how do i convert b back to the same integers in a?...

2 years ago | 1 answer | 0

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Question

Create cell array of numbers
Hi, how can i create a function that creates a cell array of number array 1:n, so the result is a cell array of string values. ...

2 years ago | 1 answer | 0

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Question

Classification tree view function - predictor categories are replaced by numbers?
Hello, I created a classification ensemble tree using categorical predictors (typically 4 or 5 classes/labels for each predicto...

2 years ago | 0 answers | 0

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Question

predictorImportance for classification trees
Hello, would the predictorImportance() function also work for classification trees (random forest, AdaBoostM1 or Bag method)? ...

2 years ago | 0 answers | 0

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Question

Solve multivariate equation using fsolve()
Hi, i have written a multivariate function f(x, a, b, c). Holding a, b, c values fixed, i want to know for what value of x the...

3 years ago | 1 answer | 0

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Question

Replace values in each column by 0 after a pre-specified search value was found in that column
Hello, i have a matrix A, for example A = [1, 1; 0.5, 1; 0.5, 0.5; 1, 1] I want to insert 0 values in each column, but only if...

3 years ago | 2 answers | 0

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Question

CreditDefaultCopula function not in my Matlab 2016a version, how to get it?
Hello, i would like to use Matlab's 2018 CreditDefaultCopula function to model defaults. How can i get this function in my Mat...

3 years ago | 0 answers | 0

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Question

Replace values in matrix by first non-zero value in previous row
Hi, how can i replace zero values in a matrix by the first occurring non-zero value in that matrix if you would loop backwards...

4 years ago | 1 answer | 0

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Question

How to calculate maximum up to current point?
Hi, how can i calculate the an array of current maxima, i.e. for each point in the array to calculate the maximum from the first...

4 years ago | 2 answers | 0

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Question

100 Random numbers given t-distribution with mu = x% std = y% and df = 100?
How can i create a 100 x 2 array with random numbers, given the following distribution: -mu = 2% -sigma = 3% -df = 100 tha...

4 years ago | 1 answer | 0

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Solved

Enlarge array
Given an mxn numeric array (A) and a 1x2 vector (sz) indicating the dimensions [p q] to enlarge each element, return an (m*p)x(n...

4 years ago

Solved

Flip the main diagonal of a matrix
Given a n x n matrix, M, flip its main diagonal. Example: >> M=magic(5); >> flipDiagonal(M) 9 24 1 ...

4 years ago

Solved

Return the first and last character of a string
Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

4 years ago

Solved

Replace May with April
For instance, if the input is input_str = 'The flowers may bloom in April'; then the output is output_str = 'The flo...

5 years ago

Solved

Which values occur exactly three times?
Return a list of all values (sorted smallest to largest) that appear exactly three times in the input vector x. So if x = [1 2...

5 years ago

Solved

Simple equation: Annual salary
Given an hourly wage, compute an annual salary by multiplying the wage times 40 and times 50, because salary = wage x 40 hours/w...

5 years ago

Solved

Sort a list of complex numbers based on far they are from the origin.
Given a list of complex numbers z, return a list zSorted such that the numbers that are farthest from the origin (0+0i) appear f...

5 years ago

Solved

Determine whether a vector is monotonically increasing
Return true if the elements of the input vector increase monotonically (i.e. each element is larger than the previous). Return f...

5 years ago

Solved

Find all elements less than 0 or greater than 10 and replace them with NaN
Given an input vector x, find all elements of x less than 0 or greater than 10 and replace them with NaN. Example: Input ...

5 years ago

Solved

Swap the first and last columns
Flip the outermost columns of matrix A, so that the first column becomes the last and the last column becomes the first. All oth...

5 years ago

Solved

Determine if input is odd
Given the input n, return true if n is odd or false if n is even.

5 years ago

Solved

Select every other element of a vector
Write a function which returns every other element of the vector passed in. That is, it returns the all odd-numbered elements, s...

5 years ago

Solved

Make the vector [1 2 3 4 5 6 7 8 9 10]
In MATLAB, you create a vector by enclosing the elements in square brackets like so: x = [1 2 3 4] Commas are optional, s...

5 years ago

Question

Surfl chart; datetime on y-axis, letters on x-axis
Hi, i am trying to make a 3d surface chart (surfl) out of a x-by-y table named 'cum_pl', which contains daily P&L numbers for x...

5 years ago | 2 answers | 0

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Question

Formula for calculating marginal risk contributions (video MATLAB for Advanced Portfolio Construction and Stock Selection Models)
Hi, i just watched the video https://nl.mathworks.com/videos/matlab-for-advanced-portfolio-construction-and-stock-selection-mod...

5 years ago | 1 answer | 0

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Find the sum of all the numbers of the input vector
Find the sum of all the numbers of the input vector x. Examples: Input x = [1 2 3 5] Output y is 11 Input x ...

5 years ago

Solved

Times 2 - START HERE
Try out this test problem first. Given the variable x as your input, multiply it by two and put the result in y. Examples:...

5 years ago

Question

How can i generate month and year strings for Datetime vectors?
How can i generate month and year concatenated strings for Datetime vectors? E.g. i have vector ['01/Jan/2015';'01/Feb/2015']...

5 years ago | 4 answers | 0