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Ask the right questions to secure the right IDL talent among an increasingly shrinking pool of talent.
The Interactive Data Language (IDL) is a high-level programming language primarily used for data analysis and visualization. First developed in the 1970s by David Stern at Research Systems, Inc., IDL has become a standard tool for astronomers and atmospheric scientists (Stern, D., 2001). The language's array-oriented operations and powerful graphics capabilities make it ideal for processing large volumes of data. It is also popular in medical imaging and remote sensing fields due to its ability to handle multi-dimensional arrays efficiently. Despite competition from open-source languages like Python, IDL's robustness continues to make it a reliable choice in scientific computing (Bowman, C., 2014).
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
An IDL procedure performs a task and does not return a value, whereas an IDL function performs a task and returns a value.
IDL arrays are used to store multiple values of the same data type. They are useful in performing vectorized operations, which can greatly improve the performance of the code.
IDL provides a system variable !ERROR_STATE which can be used to handle errors. It contains several fields like NAME, BLOCK, CODE, etc., which can be used to get information about the error.
IDL supports several data types including integer, float, double, string, boolean, byte, object references, arrays, and enumerations.
An IDL file typically contains a module that includes interfaces, methods, and data types. The interface defines methods and their parameters. Data types can be native or custom defined.
Passion can be a good indicator of how invested a candidate will be in their role. A passionate candidate is likely to be more motivated and dedicated to their work.
Most development projects require teamwork. The candidate should be able to work well with others, contributing to a positive and productive team environment.
While the role is for an IDL developer, having experience with other languages can be beneficial. It can provide a broader perspective and potentially bring new ideas or approaches to the role.
Communication is important in any job role. They need to be able to articulate their thoughts and ideas clearly, as well as understand and respond to the thoughts and ideas of others.
Problem-solving is a key skill for any developer. They should be able to demonstrate their ability to troubleshoot and solve issues that may arise during development.
This is crucial as the job role is specifically for an IDL developer. Their knowledge and understanding of the language will directly impact their ability to perform the job.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
IDL provides a class definition syntax for defining classes and objects. It supports key OOP concepts like inheritance, encapsulation, and polymorphism.
Arrays in IDL are of fixed size and all elements must be of the same type. Lists, on the other hand, can grow dynamically and can contain elements of different types.
IDL provides several functions for memory management like PTR_FREE, HEAP_GC, etc. It's important to free up memory that is no longer needed to prevent memory leaks.
An IDL interface typically contains methods and attributes. Methods define the operations that can be performed, and attributes define the data that can be accessed.
A multidimensional array can be created in IDL using the ARRAY function. For example, ARRAY(3,3,3) creates a 3x3x3 dimensional array.
At this stage, a skilled IDL engineer should demonstrate proficiency in IDL programming language, strong analytical skills for problem-solving and a good understanding of data analysis techniques. Red flags include lack of detail in their process explanation, inability to solve complex problems or unfamiliarity with key IDL functions.
print, 'Hello, World!'a = findgen(10)a = indgen(10)
b = a[5:8]thread, /JOIN_ALLobj_new, 'myClass', thisVariableprint, total(!pi * findgen(10)^2)The final few interview questions for a IDL candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.
Versioning in IDL can be handled by defining new interfaces for major changes, while minor changes can be handled by adding methods to existing interfaces. This ensures backward compatibility.
Key considerations would include ensuring the interface is well-defined and stable, designing for scalability and performance, and providing clear and comprehensive documentation.
Performance in IDL can be optimized by using vectorized operations, managing memory efficiently, and using compiled routines instead of interpreted ones.
Local variables are defined within a function or procedure and can only be accessed within that scope. Global variables are defined outside all functions and procedures and can be accessed anywhere in the program.
Object graphics in IDL provide a higher level of abstraction and flexibility compared to direct graphics. They allow for interactive manipulation of graphics and better control over the layout.
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