Wednesday, June 29, 2016

Python script to rename multiple files/folders

In this post, am going to walk you through a process that could be boring, repetitive, or just pron to errors/mistakes if done manually. This process is: renaming multiple files/folders with Python script.

If you ever found yourself in a situation where you have to rename several files/folders, then this Python scripting tutorial will help you.

Let's get started!

I have a folder containing 200+ pictures from my digital camera with the picture names like this format: "IMG-20160530-WA0000.jpg" as seen below.

Monday, June 27, 2016

How to remove no-data values on raster image data in QGIS

Assuming you are working with an image with part of it containing no-data (that is blank) with uniform color in the no-data area.

From the loaded rater data below; You will notice the black pixels at the right and bottom of the image. Let’s remove that in these step-by-step guide.

Note that the no-data values here is black color pixels which has 0 as the RGB value. It can be of different pixel color in some cases, so we need to know the color's RGB value.

Sunday, June 26, 2016

How to Plot a Single Set of Point Coordinate in an existing layer Using QGIS

Good day,
There are situations when using point shapefile layer in QGIS that you just need to do one of these:-
1~ Plot/add just a point?
2~ Move a point?

To Plot/add a new point or Move an existing point in QGIS within an existing point layer to a specific coordinate position, then you are reading the correct tutorial.

In other word, if you have a single set of coordinates that you want to map using QGIS, here are step-by-step instructions on how to do that.

You can create or move point features with exact (manually entered) coordinates within an existing point layer in QGIS by using any of these plugins:
~ Numerical Vertex Edit (Allows to edit a vertex in a numeric way by clicking on it.)
~ Numerical Digitize (Digitize with just the keyboard (numeric coordinates))

Step 1: Install the plugins by going to: Plugins –> Manage and Install Plugins. Search and select the plugins (Numerical Vertex Edit and Numerical Digitize) from the list and then select “install plugin” from the bottom buttons.  Once the button installs, you are ready to plot or move point features on existing point layer.

Saturday, June 25, 2016

Geo-Data Science and GIS

Hello there,

Today, I want to discuss about the Best programming language for Geo-Data Science and GIS.

What is Geo-Data Science and GIS?

Geo-Data Science: Geo-Data Science is a subset of Data science which according to wikipedia; is an interdisciplinary field about processes and systems to extract knowledge or insights from data in various forms, either structured or unstructured, which is a continuation of some of the data analysis fields such as statistics, data mining, and predictive analytics, similar to Knowledge Discovery in Databases (KDD). Source...
Geodata is information about geographic locations that is stored in a format that can be used with a geographic information system (GIS).

Geodata can be stored in a database, geodatabase, shapefile, coverage, raster image, or even a dbf table or Microsoft Excel spreadsheet.
A data scientist is someone who knows more statistics than a computer scientist and more computer science than a statistician. To be mre formal, we can say a data scientist is someone who extracts insights from messy data.

GIS: According to National Geographic Society;- A geographic information system (GIS) is a computer system for capturing, storing, checking, and displaying data related to positions on Earth’s surface. GIS can show many different kinds of data on one map. This enables people to more easily see, analyze, and understand patterns and relationships. 

Friday, June 24, 2016

How to Extract a GIS Dataset Selection into a New Dataset Layer Using QGIS

In this post, am going to talk about How to Extract a GIS Dataset Selection into a New Dataset Layer Using QGIS.

Often you will find yourself working with a large geographic dataset in QGIS and you want to select a smaller geographic section and convert it to a new file.

Consider a situation whereby you have a large dataset and you needed a new dataset out of the exsisting one to form a new dataset layer.

Here is what I mean in another word, lets say you need to have a new dataset layer of just the states in Southern part of Nigeria? Since you have a dataset layer containing all the states in the country, how would you extract out just the states in Southern part?

This is how it is done in QGIS.

~ Load your Dataset layer (Nigerain_states.shp) shapefile

~ Go to "View" menu >> Select >> Select features by Polygon

~ Draw a polygon around the states in Southern part to select them

List of Top 10 Programming Language and their Inventors

Here all time Top 10 Programming Language and their Inventors name, Year first invented, Nationality of the Inventors.

1) Java - James Gosling - 1995 - Canadian

2) C - Dennis Ritchie - 1972 - American

3) C++ - Bjarne Stroustrup - 1983 - Danish

4) Python - Guido van Rossum - 1991 - Netherlands

5) PHP - Rasmus Lerdorf - 1995 - Greenlandic

6) Perl - Larry Wall - 1987 - American

7) JavaScript - Brendan Eich - 1995 - American

8) Ruby - Yukihiro Matsumoto - 1995 - Japanese

9) Lisp - John McCarthy - 1958 - American

10) Pascal - Niklaus Emil Wirth - 1970 - Switzerland

You can find more on wikipedia
Warm regards!

The differences between a map and plan

Maps and Plans are two common terms used in the GIS industry. And in most cases the people using the system don't bother to know the differences between a map and plan, so in this post I list some of the differences between a map and plan.

(a) A map is a visual representation of an area - a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes.

Plans are a set of two-dimensional diagrams or drawings used to describe a place or object, or to communicate building or fabrication instructions. Usually plans are drawn or printed on paper, but they can take the form of a digital file. 

(b) Although most commonly used to depict geography, maps may represent any space, real or imagined, without regard to context or scale; e.g. Brain mapping, DNA mapping, and extra-terrestrial mapping.

Plans are often for technical purposes such as architecture, engineering, or planning. Their purpose in these disciplines is to accurately and unambiguously capture all the geometric features of a site, building, product or component. Plans can also be for presentation or orientation purposes, and as such are often less detailed versions of the former. The end goal of plans is either to portray an existing place or object, or to convey enough information to allow a builder or manufacturer to realize a design.
(c) Many but not all maps are drawn to a scale, allowing the reader to infer the actual sizes of, and distances between, depicted objects. A larger scale shows more detail, thus requiring a larger map to show the same area. 

Plans are usually scale drawings, meaning that the plans are drawn at specific ratio relative to the actual size of the place or object. Various scales may be used for different drawings in a set. For example, a floor plan may be drawn at 1:50 (or 1/4"=1'-0") whereas a detailed view may be drawn at 1:25 (or 1/2"=1'-0"). Site plans are often drawn at 1:200 or 1:100

(d) To communicate spatial information effectively, features such as rivers, lakes, and cities need to be labeled. Over centuries cartographers have developed the art of placing names on even the densest of maps. Text placement or name placement can get mathematically very complex as the number of labels and map density increases. Therefore, text placement is time-consuming and labor-intensive, so cartographers and GIS users have developed automatic label placement to ease this process

Because plans represent three-dimensional objects on a two-dimensional plane, the use of views or projections is crucial to the legibility of plans. Each projection is achieved by assuming a vantage point from which to see the place or object, and a type of projection

(e) A plan generally works using a smaller scale while a map uses a larger scale as it generally covers larger areas.

(f) A plan is a true scale scale representation while a map is drawn such that some features on it cannot be drawn to scale. On a map many features are represented as symbols and generalization is carried out resulting in changes in scale and displacement of features. e.g on a 1:1 million map, rivers and roads may be shown but they cannot be drawn to scale. a 5m road would be 0.005mm wide if drawn according to scale.

(g) Plans tend to be for a single or few applications while maps cover a large vary of uses e.g in exploration, military, recreation, geological, navigation e.t.c
Thanks for reading