Gnuplot/C2/Plotting-datasets-from-file/English
Visual Cue | Narration |
Slide Number 1
Title Slide |
Welcome to the tutorial on Plotting Dataset from a File in gnuplot. |
Slide Number 2
Learning Objectives |
In this tutorial we will learn to,
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Slide Number 3
Learning Objectives |
* Change the line color
and
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Slide Number 4
System and Software Requirement |
To record this tutorial, I am using
and
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Slide Number 5
Pre-requisites https://www.spoken-tutorial.org |
To follow this tutorial,
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Go to Desktop and cursor on Desktop . | Go to desktop .
We will plot a graph using the data in a text file data.txt. The file is provided in the codefiles link of this tutorial. |
Show data.txt icon in Desktop directory. | I have downloaded and saved the file on Desktop. |
Double click on the icon. | Double click on the file icon to open and view the file.
File opens in gedit text editor for me. |
Hover mouse and show on screen. | The data has three columns.
The first row consists of headings and starts with a hash. |
Point to columns. | The first column contains x axis data, 2nd and 3rd columns are two sets of y data. |
Click on the x sign. | Close the data file by clicking on the 'x' button. |
Press Ctrl+Alt+T . | Press Control, Alt & T keys together on keyboard to open the terminal. |
The terminal opens. | |
Type cd Desktop and press Enter. | Change directory to Desktop directory as seen on the screen. |
Type gnuplot and press Enter. | Type gnuplot at the command prompt and press enter to open gnuplot. |
Press Ctrl+Shift+K . | I will clear the screen to bring terminal prompt to top of the screen. |
Type plot "data.txt" using 1:2 title 'Y1' and Press Enter. | First let's make a plot from x and y1 data columns.
Enter command as seen on the screen. |
Hover mouse next to legend text. |
Here we have also added the legend text in the same command line. A graphic window opens. |
Hover mouse next to symbols. | Next, let's make the symbol size larger. |
Type set pointsize 1.5
Press Enter |
To set the symbol point size, enter command, set pointsize 1.5. |
Type replot and press Enter. | Enter command replot, to see the updated graph. |
Narration only. | Now, let’s plot both y1 and y2 data on the graph together. |
Type plot "data.txt" using 1:2 title 'Y1' , "data.txt" using 1:3 title 'Y2'
and press Enter. |
For this purpose, use the plot command as above, in series, separated by a comma.
The command is shown on the screen. |
Point mouse on y axis. | Let's set y-axis to logarithmic scale . |
Type set logscale y and press Enter.
Type replot and press enter. |
Use command set space logscale space y to set logscale.
Replot to see the result. |
Show on the screen. | The exponential data looks as a linear line due to the logarithmic scale. |
Type unset logscale y and press Enter. | To go back to linear scale for y-axis, use command, unset space logscale space y. |
Type replot and press Enter. | Please replot to see the resulting change. |
Type plot "data.txt" using 1:3 with linespoints and press Enter. | Next, let’s connect the data points for x and y2 data set, using a line.
The command is shown on the screen. |
Hover mouse next to linespoints. |
Add with linespoints in the plot command itself to add a line in the graph. |
Hover mouse next to symbol. | Next, let's change the graph properties.
Let’s change symbols to larger, filled circles and color them blue. |
Type, plot "data.txt" using 1:3 title 'Y2' with linespoint lc 'blue' lt 1 lw 2 pt 7 ps 1.5 and press Enter | Enter the command, as seen on the screen.
This command changes color, point style and style line. |
Hover mouse next to lc . | Here, lc sets line color to blue.
We can also use hexadecimal code for the chosen color. |
Hover mouse over lw . | Lw 2 sets line width to two. |
Hover mouse next to pt . | Pt 7 sets point type or symbol style to 7, which is a filled circle. |
Hover mouse next ps . | Ps 1.5 sets point size or symbol size to 1.5 . |
Show the graph with the formatting on lines and symbols. | Notice the changes in the graph as specified in the command. |
Hover mouse on y-axis scale in graph. | We may wish to change the format for axis labels on many occasions.
Here, the y-axis numbers are large values. |
Point to the y axis numbers. | We may want to use scientific notation. for the large numbers.
I will use set format command for this purpose. |
Type set format y '%0.2e' and press Enter. | Type set space format, followed by axis name.
Here it is y. Follow it by space and within single quotes percent sign 2 e. |
Type Replot and press Enter. | Enter replot to see updated graph. |
Type set yrange [1:1.5e5] and press Enter.
Type Replot and press Enter. |
use the following syntax for changing format and range.
Use set space yrange space in square brackets 1 colon 1.5e5 |
Press Ctrl+Shift+K. | This command also changes the format of y-axis.
I will clear the screen. |
Type set border linewidth 2 lc 'red' and press Enter.
Type replot and press Enter. |
We can also change the color of the border and line width.
Use the commands as shown here to change the line color to red. |
Narration only. | We may also want to have a time stamp with the graph. |
Type set timestamp and press enter.
Type replot and press Enter. |
Type set space timestamp to add time stamp. |
Hover the mouse next to the time stamp. | Notice that time stamp for the plot is displayed at the bottom of the plot. |
Type quit and press Enter. | To quit gnuplot, enter command q or type quit at the gnuplot prompt. |
Slide Number 6
Summary |
To summarize, in this tutorial, we
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Slide Number 7
Summary |
* Formatted label style to scientific notation
and
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Slide Number 8
Assignment |
For assignment activity, please do the following.
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Slide Number 9
Assignment |
* Introduce a line break in the data file between 4th and 5th line.
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Show test window, dotted line, triangle symbol and green color graph.
Show the line break in the graph. |
The completed assignment look similar to this. |
Slide Number 10
Spoken Tutorial Project |
The video at the following link summarizes the Spoken Tutorial Project.
Please download and watch it. |
Slide Number 11
Spoken Tutorial workshops The Spoken Tutorial Project team: |
We conduct workshops using spoken tutorials and give certificates.
Please write to us. |
Slide Number 12
Forum for specific questions: |
Please Post your timed queries in the forum. |
Slide Number 13
Acknowledgement |
Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. |
Thank you for joining. |