# Carson Purnell

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**Content Feed**

Question

Fastest selection of a coordinate in 3d array that fulfills a condition?

I have a relatively simple problem: I need to generate random coordinates of an array, but they must fulfill a condition. I thou...

ongeveer een maand ago | 2 answers | 0

### 2

answersThinning 3d object borders to pixel thickness

I couldn't find any existing implementation of a 3d ridge detector using hessian matrices, but I found a much simpler solution t...

ongeveer 2 maanden ago | 0

| accepted

Question

Thinning 3d object borders to pixel thickness

I am attempting to perform an operation in 3d similar to skeletonization, but instead of producing pixel-width lines I want to p...

2 maanden ago | 1 answer | 0

### 1

answerQuestion

Skeletonize 3d cylinders

I'm having trouble figuring out a reliable way to draw lines marking the midpoints of mostly hollow cylinders in a 3d volume. De...

3 maanden ago | 1 answer | 1

### 1

answerQuestion

making a label/category atlas of overlapping component images

I'm trying to create an atlas image from several different images that record occupancy of objects in a 3d space. Object type A ...

4 maanden ago | 0 answers | 0

### 0

answersQuestion

Efficient way to read variable column number data from a mixed-format text file?

I'm trying to read in specific data from .cif files, which have an unfortunate text format. A relevant section is below: the sec...

5 maanden ago | 2 answers | 0

### 2

answersSubmitted

helper_pdb2vol - PDB files to atom coord list and volume

Generates a density volume from a PDB, and provides intermediate list of atom coordinates. Dramatically faster than pdbread.

7 maanden ago | 1 download |

pdbread function doesn't read individual models

Well I ended up needed to make my own pdb reader function for my purpose (generating density maps). Here's the function if anyon...

8 maanden ago | 0

| accepted

getting a radial vector relative to a 3d shape of unknown orientation

I ended up having to write my own function to determine the major axis. https://www.mathworks.com/matlabcentral/fileexchange/113...

8 maanden ago | 0

| accepted

Merge 2 columns with strings

given column 1==A and column 2==B, this stacks those columns without sorting. %example arrays A = {'a',1;'b',2}; B = {'c',11;'...

8 maanden ago | 0

| accepted

How can the major axis of a 3d object be determined?

Seems like no matlab code has this functionality built in, so I ended up doing it myself. Demo code, assuming you already have a...

8 maanden ago | 0

| accepted

Submitted

shapeaxis - compute the axis/orientation of 3d shapes

Provides a vector describing the major axis of any 3d shape represented by a grayscale 3d array.

8 maanden ago | 2 downloads |

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:...

8 maanden ago

Question

Indexing a range of a 3d matrix incredibly slow?

I have a function that does several different operations between a source and destination matrix (each 3d), generally inserting ...

8 maanden ago | 1 answer | 0

### 1

answerQuestion

How can the major axis of a 3d object be determined?

I have some rodlike objects in 3d, below is an example. Is there a way to find its longitudinal axis? I'm trying to generate a b...

8 maanden ago | 2 answers | 0

### 2

answersHow to extract different (256,256) images from a (512,512) image and calculate the average of them?

Just loop through the step sizes and accumulate a sum, then divide by the count. imsiz = 512; im = rand(imsiz); step = 16; s...

8 maanden ago | 1

| accepted

Question

getting a radial vector relative to a 3d shape of unknown orientation

I'm trying to generate a random 'bundle' of shapes in 3d space. The shapes are long, rodlike, and approximately cylindrical, i'm...

8 maanden ago | 1 answer | 0

### 1

answerQuestion

pdbread function doesn't read individual models

The matlab pdbread function (and a similar function from a toolbox with the same codebase) appears to never correctly execute th...

9 maanden ago | 2 answers | 0

### 2

answersQuestion

How can a curved surface be generated with a thickness and density?

I've got a weird problem here. I'm trying to generate a weird feature in 3d, a cell membrane EM density. Is there some way to ge...

10 maanden ago | 2 answers | 0

### 2

answersHow to fill a 3d volume with non-overlapping structures?

To answer my own question, I went with #1. it ended up being very efficient, combined with a refactoring of the function I was u...

11 maanden ago | 0

| accepted

Question

How to fill a 3d volume with non-overlapping structures?

I have a problem that I haven't seem any general solution for in other answers. I need to randomly place arbitrary, irregular sh...

11 maanden ago | 1 answer | 1