Ranipv076: Created page with " {| border=1 || '''Visual Cue''' || '''Narration''' |- || '''Slide Number 1''' '''Title Slide''' || Welcome to the tutorial on '''Matrices and Contours''' |- || '''Slide..."

2020-12-08T13:38:30Z

Created page with " {| border=1 || '''Visual Cue''' || '''Narration''' |- || '''Slide Number 1''' '''Title Slide''' || Welcome to the tutorial on '''Matrices and Contours''' |- || '''Slide..."

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{| border=1
|| '''Visual Cue'''
|| '''Narration'''

|-
|| '''Slide Number 1'''

'''Title Slide'''
|| Welcome to the tutorial on '''Matrices and Contours'''

|-
|| '''Slide Number 2'''

'''Learning Objectives'''
|| In this tutorial, we will

* Plot a 2D matrix heatmap
* Read file headers for axis tics
* Plot a heat map for the matrix
* Add contours in a 3D plot and
* Label the contours

|-
||

'''Slide Number 3'''

'''System and Software Requirement'''
|| To record this tutorial, I am using

* '''Ubuntu Linux''' v 16.04 OS
* '''gnuplot''' 5.2.6 and
* '''Gedit''' 3.18

|-
||

'''Slide Number 4'''

'''Pre-requisites'''

[https://www.spoken-tutorial.org/ https://www.spoken-tutorial.org]
|| To follow this tutorial,

* Learners must be familiar with the basics of '''gnuplot'''.
* Please visit this site for pre-requisite tutorials.

|-
|| '''Slide Number 5'''

'''Code files'''
|| * Files used in this tutorial are provided in the '''Code files''' link of this tutorial.
* Please download and extract them.
* Make a copy and then use them while practising.

|-
|| Screenshot of '''Desktop''' showing input file.
|| I have saved the input file '''results.txt '''on '''Desktop'''.

Let’s check file format by opening the file in '''gedit''' text editor.

You may use the editor of your choice.

|-
|| Show '''results.txt''' file in text editor.

Point to headers and matrix elements.
|| The first row is row header.

The first row is headers referring to students from S1 to S20.

First column is also a header. It lists the subjects they appeared for exam.

The matrix elements are the marks obtained.

|-
|| Close '''gedit'''.
|| Let’s close the text editor.

|-
|| Press '''Ctrl+Alt+T'''.
|| I will also open a '''terminal'''.

|-
|| Type '''cd Desktop''' and press '''Enter'''.
|| Change the '''directory''' to '''desktop'''.

|-
|| Enter the command '''gnuplot'''.
|| Open '''gnuplot''' from the '''terminal'''.

|-
|| Press '''Ctrl+L'''.
|| I will also clear the screen.

|-
|| Type,

'''plot 'results.txt' matrix rowheaders columnheaders with image'''

and press '''Enter'''.
|| Enter the plot command as seen on the screen.

Here, the matrix name '''results.txt''', is in single quotes.

Use the syntax and whitespaces as seen on the screen for the command.

Follow it with matrix, rowheaders, column headers.

Specify to plot '''with image''' and press '''Enter'''.

|-
|| Show graphics window.
|| In the graphics window, a 2D heatmap image of the matrix appears.

|-
|| Hover mouse over '''x''' and '''y''' tics
|| The x and y axes tics are represented by strings.

They are the student names.

The subjects which they have appeared for examination is also seen.

|-
|| Cursor on the color scale bar.
|| Notice the palette setting is indicated in the color scale bar.

|-
|| Hover mouse over color scale bar.
|| The '''color palette''' can be customized as desired.

Let’s change to a custom palette.

|-
|| Type,

'''set palette defined (0 "dark-violet", 1 "sandybrown", 2 "grey80", 3 "blue", 4 0.5 1 0.5, 5 1 1 0, 6 1 0.5 0, 7 1 0 0, 8 0.5 0 0)''' and press '''Enter'''.
|| Now I will define a new color palette.

Type the following command and press Enter.

|-
|| Hover mouse over '''2 “grey80”''' and '''5 1 1 0''' .
|| Here, I define the color for each range in the colorbar.

|-
|| Type, '''replot''' and

press '''Enter'''.
|| '''Replot''' to see the results.

You may explore more on '''color palette''' options if desired.

|-
|| Write on the Screen, Use the command, '''help color palette.'''
|| Use the command, '''help color palette''' for learning further.

|-
|| Go to '''gnuplot terminal''' prompt.
|| Go back to the '''terminal'''.

|-
|| Type '''help palette''' and press '''Enter'''.
|| Use the command '''help palette''' to learn more about palette setting.

|-
|| Press '''Ctrl+L'''.
|| I will clear the screen.

|-
|| Cursor on the graphics window.
|| Let’s now plot contours and label the contours in a 3D plot.

I will open '''gedit''' text editor to write a short script.

|-
|| Cursor on '''gedit '''text window.
|| You may open the text editor of your choice.

|-
|| Type '''#contour plot and labels'''

and press '''Enter'''.
|| First, write a comment line, starting with a hash, as seen here.

Next let's incorporate contours in the plot.

|-
|| Type, '''set contour base''' and press '''Enter'''.
|| Then set the contour base with the command, '''set contour base'''.

'''Set contour''' command is used for grid type data and is used with '''splot''' command.

Here, '''base''' specifies that, the contours are drawn on the grid base.

|-
|| Type, '''set isosamples 50,50 '''and press '''Enter'''.
|| Set the grid for '''isosamples''' to 50 comma 50.

|-
|| Type, '''set style increment default''' and press '''Enter'''.
|| Set the increment to default value.

This increments successive line styles in the graph.

|-
|| Type, '''set cntrparam levels auto 10''' and press '''Enter'''.
|| This command determines the z values for which the contours are to be drawn.

We can also specify the way contours are drawn.

Let’s also set the contour levels. I will set it to autoscale.

|-
|| Type, '''set cntrlabel format '%8.3g' font ',7' start 5 interval 20''' and press '''Enter'''.
|| Now, specify a desired font for the contour label, start and the interval.

|-
|| Type, '''set style data lines''' and press '''Enter'''.
|| Set the style to lines for the contours.

|-
|| Type '''set autoscale''' and press '''Enter'''.
|| Set axis range for x and y axis as seen here.

|-
|| Type, '''splot x**2+y**2 with lines notitle , x**2+y**2 with labels''' and press '''Enter'''.
|| Now, let’s draw the plot with '''splot''' command.

|-
|| Press '''Ctrl+S'''.
|| I will save the file. Press '''Ctrl+S'''.

|-
|| Give file name '''contour.dem''' in '''Desktop''' directory.

Click on '''Save'''.
|| I will give file name '''contour.dem'''.

Save the file in '''Desktop''' directory.
|-
|| Minimize '''gedit''' and to the '''terminal'''.
|| Minimize '''gedit''' and go to the '''terminal'''.

|-
|| Type, '''cd Desktop '''and press '''Enter'''.
|| I will change the directory to '''Desktop'''.

|-
|| Type, '''gnuplot''' and press '''Enter'''.

Press '''Ctrl+L'''.
|| I will also open '''gnuplot''' and clear the '''terminal'''.

|-
|| Type, '''load 'contour.dem' '''and press '''Enter'''.
|| Let’s load the script file with the '''load '''command as seen on the screen.

|-
|| Cursor on the graphics window, on the surface.
|| The graphics window opens.

Notice the surface plot.

|-
|| Cursor on the contours.
|| The contours are seen on the base as we specified in the script file.

They are also labeled.

Let’s modify the script file to write the 3D data to a table.

|-
|| Close the graphics window.
|| Close the graphics window.

|-
|| Go to the script file.
|| Go back to the script file which is open in '''gedit''' text editor.

|-
|| Type, '''pause -1 'Press enter to continue'''' and press '''Enter'''.
|| I will add a '''pause''' command as seen on the screen.

|-
|| Type, '''set table 'contour.dat'''' and press '''Enter'''.
|| Next set table and specify an output file name.

|-
|| Type, '''splot x**2+y**2''' and press '''Enter'''.
|| Let’s '''splot''' the function as seen.

This will generate data points in the specified file name.

|-
|| Type, '''unset table''' and press '''Enter'''.
|| Unset the table as seen on the screen.

|-
|| Cursor on the '''graphics '''window.
|| Usually the plot will appear small if we '''splot '''the function directly.

|-
|| Type,

'''set xrange [-9:9]'''

'''set yrange [-9:9]'''
and press '''Enter'''.
|| I will also set '''x''' and '''y''' axis range.

|-
|| Type, '''plot 'table-contour.txt' using 1:2:3 with lines, '' u 1:2:3 every 50 w labels notitle''' and press '''Enter'''.
|| Next, plot the contours with the 2D '''plot''' command as seen.

|-
|| Save the file, minimize '''gedit''' and go to the '''terminal'''.
|| Save the file, minimize '''gedit''' and go to the '''terminal'''.

|-
|| Enter the command '''gnuplot'''.
|| Open '''gnuplot''' from the '''terminal'''.

|-
|| Enter command '''load 'contour.dem'''' .
|| Load the script file as seen on the screen.

|-
|| Cursor on the graphics window.
|| Notice the first plot which we saw earlier.

|-
|| Go to the '''terminal''' and press '''Enter'''.
|| Go to the '''terminal''' and press '''Enter'''.

|-
|| Cursor on the graphics window.
|| Notice the 2D contour plot.

|-
|| Cursor on the graphics window.
|| Learner is encouraged to lookup the details for '''dgrid3d''' command.

Use the '''help''' command in '''terminal''' for this purpose.

|-
|| Close the graphics window.
|| Close the graphics window.

|-
|| Type '''help dgrid3d''' and press '''Enter'''.
|| In the '''terminal''' type '''help dgrid3d''' to access the help documentation on it.

|-
|| Press '''Ctrl+C'''.
|| Learner may pause the video and explore the details.

Let’s exit the help section by pressing '''Control-C'''.

|-
|| Type '''q''' and press '''Enter'''.
|| Enter the command '''q''' or '''quit''' to quit '''gnuplot'''.

|-
|| Close the '''gedit''' window.
|| Close the '''gedit''' window.

|-
|| '''Slide Number 6'''

'''Summary'''
|| Now let's summarize.

In this tutorial, we learned,

* About a 2D matrix
* Plotted the data in the 2D matrix as heatmap
* Plotted, a 3D function with contours on the base with splot command
* Labeled the contours
* Plotted the contours of the 3D function in a 2D plot

|-
|| '''Slide Number 7'''

'''Assignment'''
|| For assignment activity, please do the following.

For the function x2*y2,
* Change '''rgbformulae''' setting to change colors
* Plot contours with '''set contour surface''' and with '''set base both'''
* Notice the position of the contours that is plotted.

|-
|| '''Assignment picture'''
|| The completed assignment may look similar to this.

|-
|| '''Slide Number 8'''

'''Spoken Tutorial Project'''
|| This video summarises the '''Spoken Tutorial''' Project.

Please download and watch it.

|-
|| '''Slide Number 9'''

'''Spoken Tutorial workshops'''
|| The '''Spoken Tutorial''' Project Team
* conducts workshops and
* gives certificates.

For more details, please write to us.

|-
|| '''Slide Number 10'''

'''Forum for specific questions:'''
|| Post your timed queries in the forum.

|-
|| '''Slide Number 11'''

'''Acknowledgement'''
|| '''Spoken Tutorial''' Project is funded by MHRD, Government of India.

|-
||
|| This is Rani from '''IIT, Bombay'''.

Thank you for joining.

|-
|}

Gnuplot/C4/Matrices-and-Contours/English - Revision history

Ranipv076: Created page with " {| border=1 || '''Visual Cue''' || '''Narration''' |- || '''Slide Number 1''' '''Title Slide''' || Welcome to the tutorial on '''Matrices and Contours''' |- || '''Slide..."