abu002

Manipulating a string in MATLAB

Manipulating a string in MATLAB.

Following the previous post, where a string can be modified at vowel locations, and written over several times in a cyclic order, this post is about some more  vowel manipulation using Matlab.

So, after the previous post, my colleagues at work gave me a new challenge to do in Matlab. The problem statement was :Matlab is given a string (aka statement) which is a general combination of a lot of vowels and constants that make up words. Say for example like this:

monkeys like eating bananas that are ripe and yellow.

Assuming all the letters are in small ( program can be edited to have letter sin both caps and small as well) , the program reads through the statement and replace the last vowel in every word with nothing , or just truncates it. To add to the challenge the solution must be done without using an inbuilt library functionality.

Therefore after doing what has been asked for, the final output should be this :

monkys lik eatng banans tht ar rip nd yellw.

So,  attempted to solve this using matlab and you can find the code here:

Code here:

The way I solved is this. I am sure there can be several other ways to do that, and I am looking forward to hear from you in the comments section.

My algorithm:

  1. Add a space to the end of the string.
  2. Find the number of spacer by iterating through the string and checking for integer value of each character. The ASCII value of space is 32.
  3. The number of space is equal to the number of words then. Since we have added an extra space to the end.
  4. Now ask matlab to loop through each word. This can be done by space locations and first character. It can be made simpler by adding a space to the beginning of the statement as well. Then the whole string is homogeneously spaced.
  5. Fing the index of vowels in each word.
  6. list the index of each vowel
  7. Remove it by using a logical indexing operation.
  8. Print it.
  9. And you are done !

Download code here.

Let me know about your algorithm in the comment sections.

 

 

 

 

 

brownfox

Writing Impositions in Matlab

Writing Impositions in Matlab

This post is for students who do not do their homework (like me when I was in school) and are punished with writing impositions. The imposition would usually be writing something like a very long statement with no meaning several times. Like back in my school days, when we were told to write them on paper using a pen or pencil. But these days students and truants are asked (ordered!) to write them in a word-processing software. Well, we can think of using the classic trick of Ctrl+C and Ctrl+V, but it depends on the imposition type, right!

Like for say here, we are asked to write this statement :

“The quick brown fox jumps over the lazy dog”.

And the teacher asks you to change every vowel with its preceding vowel in each iteration.That would mean , in my first statement, a is replaced to e, e is replaced by i, i is replaced by o, o is replaced by u, and u is replaced by a. In subsequent iterations, the replaced vowels are replaced by their preceding vowel. And this has to be done say 100 times. (Quite a tough punishment!). This case can not be done in MS Word or any other word processor, so the student has to do type this manually each time or just do his homework instead.

However, good news! I have a Matlab code for you, which will do it for you however number of times you want to write. In the end, all you have to do copy the final output to a word processor  and get the print. The code is as simple it can be without using any library functions so that people with no knowledge about Matlab can still use, because then it is just English to understand.

You can get the code here, and use an online compiler to run it .

Download code here:

 

 

datasync

Data syncing and backUP

When we look around us , we are surrounded by data and a lot of information. But in this post I will not be talking about those objects (as they are called in object oriented programming). In this data refers to all the qualitative and quantitative set of information and variables we have stored in our computer. These data be it just collected, reported or even analysed are very crucial for every one. Every individual encounters different type of data. This page will classify different types of data for interested readers.

This post focuses on data back up and syncing. In simple words, it is the act of replicating data between two storage units, but the storage needs to be mirrored. That means change to one will be reflected to the other and vice versa. The advantage of this is that it saves a lot of time than the general copy pasting, and of course it is the ability to preview the changes before they are actually made.

For syncing there are various software in the market, some commercial and some open source applications.  Personally ,I use SyncToy, and have described the process to sync in this post. The good things about this software is it is a freeware and it has a very simple GUI to get the work done.

So here we go.

  1. Install the SyncToy software by downloading it from here.
  2. Once installed, open up the application.
  3. On the window that pops up, click on Create New Folder Pair.
  4. Now choose the folders that you want to sync. Left is the source folder path, Right is the target source folder path.
  5. Click NEXT.
  6.  The next window that follows asks about the type of sync, viz;
    Synchronize: Updates files both ways…keeping changes like renames, deletions and edits to either folder contents the same between the two.
    Echo: New and updated files are copied left to right. Renames and deletes on the left are repeated on the right.
    Contribute: New and updated files are copied left to right. Renames on the left are repeated on the right. No deletions.
  7.  I will recommend using the Contribute option.
  8.  After that, name your syncing action. Choose a suitable name in case you are syncing between different target sources. Click FINISH
  9. On the next window, click RUN, to see the software syncing your data from the source path to the target path.
  10. Once done, click CLOSE to see the report of syncing
  11. To schedule the syncing automatically,  go to Task Scheduler option in windows 7.
  12. Click on Create basic Task
  13. Next type a little name and description to the task like ” DataSYNC SyncToy”
  14.  Go to the trigger option, and select the frequency of syncing up to your convenience.
  15. In the Action tab of the window,  type “C:\Program Files\SyncToy2.1\SyncToy.exe” where it asks for Program/Script.
  16. In the add argument section, type -R
  17. Click Finish to get things done.
  18. Have it a go !
mavg

A simple moving point average in Matlab

A simple  moving point average in MATLAB.

A moving average or a rolling average is one of the most common smoothing technique used to extract a good signal out of a very random noisy signal. This technique is usually used to see the behavior of a function or  a signal, when the physical parameters and environment have an erroneous effect on the measured signal.

Given a series of numbers and a fixed subset size, the first element of the moving average is obtained by taking the average of the initial fixed subset of the number series. Then the subset is modified by “shifting forward”; that is, excluding the first number of the series and including the next number following the original subset in the series. This creates a new subset of numbers, which is averaged. This process is repeated over the entire data series. The plot line connecting all the (fixed) averages is the moving average. A moving average is a set of numbers, each of which is the average of the corresponding subset of a larger set of datum points. A moving average may also use unequal weights for each datum value in the subset to emphasize particular values in the subset.

The general technique involves finding the mean  from an equal number of data on either side of a central value. This ensures that variations in the mean are aligned with the variations in the data rather than being shifted in time. There can be some anomalies when the variation is not uniform as well, but this will not be discussed here.

There can be different types of moving point averages like  the

  • Cumulative moving average
  • Weighted moving average
  • Exponential moving average
  • Modified moving average, and
  •  Regression  moving average methods

In this post I have attached a MATLAB code to do a simple moving average. This code can be used to smooth a signal with some nice feature but with a small background noise without compromising on the data value. But be careful on the window span of the average for your own data.

Find the code here:

 

 

Untitled

Multi-curve fitting in Origin Pro.

Multi-curve fitting in Origin Pro.

Origin is a data processing and analyzing software and probably one of the most popular software choice to analyse data in industry,academia and laboratories. The versatility of the software is its easy to use, updates in real time, robust analysis, import and export capabilities even to LATEX. I will recommend this software to anyone who spends lot of time crunching numbers and getting some sweet results from it.

Yes, Matlab can do curve fit as well using cftool option. Yet there are some functions which can get a bit complicated with matlab fit tool, and also the energy to write a code when you can use ready to use  functions( in thousands) to do that for you.

In this article, I have attached a video tutorial to show how a double Lorentz function is fitted to a signal data to get the half width, peak center etc of the signal.

You can find the video in the link here.