Sunday, April 23, 2017

Installing wxPython on Python 3.x

Few years ago I wrote this blog post on "How to install wxPython (Phoenix) on Python 3.x". Since then, a lot has happened including the release of "wxPython 4.0.0a1"


So, today I decided to install the latest alfa release on my python 3 anaconda setup. I went to wx PyPi url downloaded the wheel file locally and ran: pip install wheel_file_name to install successfully as seen below.



I tested the installation, by importing wx and it work perfectly.



Congrats WX is now officially on python 3

Monday, April 10, 2017

Cleaning big data CSV file with Python

Hello there,

I know I can open a CSV file in a spreadsheet software like MS Excel or a text editor like NotePad++ and edit/clean its contents (by removing unwanted contents).

In a situation where by the CSV file is very big (big data - it contains millions of rows and columns), if you try to open such file in a spreadsheet software or a text editor there is possibility of memory error from the software you are using as seen in the image below. This excel error says: "File not loaded completely", the file appeared to be beyond MS excel capabilities.



This is where using a data oriented language such as Python comes in handy. Python pandas module can efficiently load/open and process such heavy duty big data files without much difficulties.

Saturday, April 1, 2017

Windows PostgreSQL installation Error - Unable to write inside TEMP environment variable path

Here is the solution to the "PostgreSQL installation Error - Unable to write inside TEMP environment variable path" on windows PC.

I downloaded the latest version of PgAdmin4 for PostgreSQL 9.6 from EnterpriseBD. When I tried to install it, I got this error massage: There has been an error, Unable to write inside TEMP environment variable path.




Solution to the Error


Now, to solve this error on your windows machine proceed as follow:-
1- Locate your windows sytem32 folder at: C:\Windows\System32



2- Inside the folder, find regedt32.exe file and run/open it


3- Navigate to this folder: HKEY_CURRENT_USER >> Software >> Microsoft >> Windows Script Host >> Settings



4- Right click on the "Enable" icon and select "Modify"



5- Change"Value Data" from 0 to 1 and click on "OK"



6- Close the Registry Editor and you are done.



Thanks for following.

Python break, continue and pass within Try... Except block

Hello there,

When using loops in python, there are situations when an external factor may influence the way your program runs.  You may want your program to exit a loop completely, skip part of a loop before continuing, or ignore that external factor. You can do these actions with break, continue, and pass statements respectively.

The "pass" statement is a no-operation (meaning that it doesn't do anything). The program just continues to the next statement, which is why you get an error.

The "break" statement exits the loops and continues running from the next statement immediately after the loop. In this case, there are no more statements, which is why your program terminates.

The "continue" statement restarts the loop but with the next item.

Sample Code

for letter in 'Python':
   if letter == 'h':
      break # continue pass
   print ('Current Letter :', letter)


Testing the above code for: break, continue and pass will yield different results as seen below:-





If we introduce a "Try ... Except" block and intentionally call an error, only pass will print the error statement at the end of the block statement.




Thanks for reading.

Sunday, March 26, 2017

Assigning single attribute to multi geometric features in QGIS

There are situations when you will want as many as possible geometric features within a shapefile layer to share the same attribute information within the attribute table.

This kind of scenario is commonly seen when representing Islands. The attribute data is the same, but the geometric representation of the Islands (in polygon) will be separated from each other to give way too water bodies.

As an example, am going to use a Nigerian state the has Islands (Bayelsa state). So, to digitize Bayelsa into wards polygons we have to deal with Islands. And here I have three polygons representing the same ward with ward_code 12 as seen below.

So, the task here is to merge or combine these same attributes into one and all the three polygons will share that same attribute information/row.



In QGIS, to make multiple polygons share the same attribute proceed like thus:-
1) First digitize the Islands polygons and assign the same attributes as usual
2) Go to Vector Menu >> Geometry Tools >> Singleparts to Multiparts


3) The next window will prompt you for the input layer (from a drop-down list) and the Unique ID field (Ward_Code) and you can specify an output file name. Select the appropriate information and click on run.


4) You should now have multi polygons sharing one row of your attribute table


Alternative method


Alternatively, you could use the "Merge Selected Features" command available in the Advanced Digitizing Toolbar as seen below:-


Select the polygons you want to merge there attributes and click on "Merge Selected Features" within the "Advanced Digitizing Toolbar", configure the attributes accordingly and click on "Ok".


That is it.
Thanks for following.

Wednesday, March 22, 2017

Using Python OpenCV to detect human face on Nigeria currency notes

Hello,

Below is a short video clip of a project am working on. It shows you about: Using Python OpenCV and Haar Cascade for Detecting human face on Nigeria currency notes




Happy viewing!

Saturday, March 11, 2017

How to merge multiple shapefile layers into one big shapefile layer

In QGIS, there are two common ways to merge multiple vector layers into one big vector shapefile layer. Namely:-

1) Using "Merge Vector Layers"
2) Using MMQGIS Plugin

I will only talk about the first option, since it is the default option made available in QGIS. For the second option, you will have to install the MMQGIS Plugin accordingly.


Merging multiple vector layers using "Merge Vector Layers"


This function is available under the menu Vector | Data management tool. You can merge all files in the input directory or select specific files in the input directory.






This algorithm combines two vector layer of the same geometry type into a single one. If attributes tables are different, the attribute table of the resulting layer will contain the attributes from both input layers.

The same applies as for MMQGIS Plugin: merged layers must all be of the same geometry type. Also, if the source layers have different attributes fields, the merged file will contain all fields, but with NULL values inserted when a source layer does not have a specific field.


Thanks for following.

Saturday, March 4, 2017

How to download Satellite or Google earth Images with High Resolution

Hey there,
Few years ago, I published a YouTube video demonstrating how to do this using El-Shayal GIS software.


Since then, many things have changed including OS etc. So today, I decided to add more options to the list.

There are multiple solutions for downloading a satellite image at high resolution. Some commonly used solutions are listed below:-

1- AutoGR software

This a powerful geometry coordinate and statistical software.




2- Map Puzzle software

If you want to download some map location from Google Maps, Bing Maps or any other map service, Map Puzzle is just what you need! It will allow you to save your map locations into high resolution images (jpg, gif, png, bmp, tiff). The only thing you need to do is to enter GPS coordinates or address by GeoCoding, hit "Download" and you are done! The map has been saved into to your computer. It works on Windows XP, Windows Vista, and Windows 7. Requires no installation and its FREE.




3- Elshayal software

Elshayal Smart is a freeware map editor app filed under mapping and made available by Elshayal Smart Web on Line Software for Windows.




4- SAS planet software

SASPlanet is a program designed for viewing and downloading high-resolution satellite imagery and conventional maps submitted by such services as Google Maps, DigitalGlobe, Kosmosnimki, Yandex.Maps, Yahoo! Maps, VirtualEarth, Gurtam, OpenStreetMap, eAtlas, Genshtab maps, iPhone maps, Navitel maps, Bings Maps (Bird's Eye) etc., but in contrast to all these services all downloaded images will remain on your computer and you will be able to view them, even without connecting to the internet. In addition to the satellite-based maps you can work with the political landscape, combined maps and maps of the Moon and Mars.




5- Google map downloader software

Google Maps Downloader helps users design custom maps by using geographical coordinates. Maps downloaded through this app can be arranged together to form one large map, or viewed individually. The Google Maps Downloader interface is practical and user-friendly.



6- Universal Maps Downloader

Universal Maps Downloader is a tool that help you to get small tile images from Google Maps, Bing maps, OpenStreet Maps, Yandex Maps, Ovi Maps, MapQuest Maps, etc. All downloaded small images are saved on the disk. You can view downloaded maps by Maps Viewer Or you can combine them into a big bmp, jpg or tif file by Maps Combiner, and also you can export all tiles into a MBTiles format database.




7- Global Mapper

Global Mapper is an affordable and easy-to-use GIS application that offers access to an unparalleled variety of spatial datasets and provides just the right level of functionality to satisfy both experienced GIS professionals and beginning users.




8- USGS Earth Explore





9- BigEast Map Downloader



There are definitely more than those mentioned above. If you know any that is worth knowing feel free to list it in the comment box below.


Thanks for reading

Thursday, February 16, 2017

How I was hacked and lost my 2017 freelance earnings

This was really painful, I was hacked and my freelance 2017 earnings were stolen away! I will share my experience and how to protect yourself from potential hacking attacks.

I work as freelancer and used Payoneer to collect my earnings. On the 14/02/2017 (coincidentally, on Valentine's day of 2017) a supposed potential client contacted me with a project request and sent me an MS document file supposedly to contain more detailed description about the project. But unfortunately, the client was a fake and he was just a hacker looking to collect innocent peoples password to there online bank accounts.



The MS document file he sent to me actually contains some VB macro scripts that runs in the background of a PC to extract/grab login credentials saved on the web browser.

Few hours after I opened the file, I got notification that my funds were been transferred out of my account  an unknown email account tied to payoneer and that was how it all happened.

Honestly it sucks to see a potential client turning out to be a hacker. See (image above) the message he sent to me and I was looking up to working with a legitimate buyer, but unfortunately I was wrong.

The hacker transferred or stole my funds to this payoneer email account at: baland.v@yandex.ru

I know my God will never allow him go free! I have reported this issue already to my God and other relevant authorities.


How to protect yourself from potential hacking attacks


1- Never save important logins details on your web browser, even if you are working from your personal computer. Device a way of saving/remembering your passwords that no script can read remotely.

2- Never trust any MS doc file that contains VB macros. If you most open such file make sure you are not connected to the internet or at least use a different trash PC to open it.

3- Always use anti virus to scan files you received (especially from first time clients) and change your login credentials regularly.


I hope this safes someone out there from being the next victim.
Stay safe!

Wednesday, February 1, 2017

Essential tools or Websites to help you understand, test and generate regular expressions

Hello there,

Recently, I was working on a project that requires me to search through bunch of text and identify some matched patterns within the text, this is what "regex" is good at. So I thought of finding a tool that will ease my way through the project and fortunately, there are many of such tools on the internet.

I wrote this post just to highlight and share with you some of the regex tools I have tested. Just in case you didn't know what regex is here is a quick intro....

RegEx written in full as "Regular Expression" is a pattern that consist of rules used to match a certain set of strings. Regular Expressions are an essential part of any programmer’s toolkit. They can be very handy when you need to identify, replace or modify text, words, patterns or characters.

RegEx is a concept that is found in any programming language. The syntax of regular expressions is the same for all programming and script languages.
Below, you will find tools that are primarily associated with a programming language while others are generic to all languages.

Here is the list:-


  • http://pythex.org
  • http://regexpal.com/
  • https://regex101.com
  • http://www.regextester.com
  • http://regexr.com
  • https://www.regexbuddy.com
  • http://regular-expressions.mobi
  • http://regexlib.com
  • https://regexone.com
  • http://www.regexter.com/
  • http://www.rubular.com
  • http://kodos.sourceforge.net
  • http://www.txt2re.com
  • http://buildregex.com
  • http://www.regexe.com
  • http://www.regextester.com
  • http://www.phpliveregex.com
  • http://regexstorm.net





Useful Tutorials:

1- What are the best resources for learning RegEx?
2- Essential Guide To Regular Expressions: Tools and Tutorials
3- Regular Expressions: 30 Useful Tools and Resources


Thanks for reading