RPR-Console
Using the R console
Keywords: The console, arrow keys, ctrl-enter to execute code
Contents
This unit is under development. There is some contents here but it is incomplete and/or may change significantly: links may lead to nowhere, the contents is likely going to be rearranged, and objectives, deliverables etc. may be incomplete or missing. Do not work with this material until it is updated to "live" status.
Abstract
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This unit ...
Prerequisites
You need to complete the following units before beginning this one:
Objectives
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Outcomes
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Deliverables
- Time management: Before you begin, estimate how long it will take you to complete this unit. Then, record in your course journal: the number of hours you estimated, the number of hours you worked on the unit, and the amount of time that passed between start and completion of this unit.
- Journal: Document your progress in your Course Journal. Some tasks may ask you to include specific items in your journal. Don't overlook these.
- Insights: If you find something particularly noteworthy about this unit, make a note in your insights! page.
Evaluation
Evaluation: NA
- This unit is not evaluated for course marks.
Contents
Typing code or executing it?
As you have seen in the R script ...
- you can type, or copy/paste code into the R or RStudio console, or if you are working with the R script in R or RStudio, just execute from the script.
In principle, commands can be copied by you from the Wiki and pasted into the console, or into a script (i.e. a text-file of R commands that can run as a program) - obviously, you don't need to copy the comments. In addition, I use syntax highlighting on R-code, to colour language keywords, numbers, strings, etc. different from other text. This improves readability but keep in mind that the colours you see on your computer may be different.
However, note the following: while it is convenient to copy/paste code, you don't learn how to write code through that. Practice has shown that it is better to actually type commands, even if you are just re-typing code from a book or online. Actively typing out the code character by character ensures you are reading and translating the code, and notice if anything is not entirely clear.[1] In computer code, every single character matters. For example, I expect that by typing out commands you will be much less likely to confuse = with <- or even ==. Also, you will sometimes mistype and create errors. That's actually good, because you quickly learn to spot errors, fix them, and resume. That way you build confidence.
However, for the project files we load from GitHub - these are too long to be retyped by you. Select the line, or parts of the line, or a larger block of code that you want to execute, then press <command> R, or <command><enter> (depending on your operating system) to execute the selected block. In this case you'll need extra effort to discipline yourself to read and understand every single character and command. The point is not to execute the scripts. The point is to understand their contents. The best way to do this is to edit the code, vary parameters, try alternatives and in general play.
However, actually working with code is another story. In this case scripts are indispensable for development. I type all steps of a typical analysis into a script - in this way I can always come back and reproduce the analysis: this makes the work reproducible. And I execute commands from the script, not the console - that's the easiest way to modify and develop. Making script and console work hand in hand is the way to work with R. There are four major advantages:
- The script is an accurate record of my procedure so I know exactly what I have done;
- I add numerous comments to record what I was thinking when I developed it;
- I can immediately reproduce the entire analysis from start to finish, simply by rerunning the script;
- I can reuse parts easily, thus making new analyses quick to develop.
- If I keep my script under version control, I can return to previous versions and undo errors. That was number five.
User interface
Both R and RStudio have a GUI[2] to lay out common tasks. For example, there are a number of menu items, many of which are similar to other programs you will have worked with ("File", "Edit", "Format", "Window", "Help" ...). All of these tasks can also be accessed through the command line in the console.
In general, GUIs are useful when you are not sure what you want to do or how to go about it; the command line is much more powerful when you have more experience and know your way around in principle. R gives you both options.
Let's look at some functions of the R console and associated windows that relate to how you work, not what you do.
Further reading, links and resources
Notes
- ↑ I think we are using a predictive mental model when we type - something like an inbuilt autocorrect-suggestion mechanism; thus if you type something unfamiliar or surprising (e.g. a subtle detail of syntax), you will notice and be able to figure out the issue. Pasting code by contrast is merely mechanical.
- ↑ A GUI is a Graphical User Interface, it has windows and menu items, as opposed to a "command line interface".
Self-evaluation
If in doubt, ask! If anything about this learning unit is not clear to you, do not proceed blindly but ask for clarification. Post your question on the course mailing list: others are likely to have similar problems. Or send an email to your instructor.
About ...
Author:
- Boris Steipe <boris.steipe@utoronto.ca>
Created:
- 2017-08-05
Modified:
- 2017-08-05
Version:
- 0.1
Version history:
- 0.1 First stub
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