Humdrum lab 5

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Revision as of 23:40, 30 April 2018 by Craig (Talk | contribs) (Plotting with Gnuplot)

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This lab is about plotting data, and doing further analysis of the raw data extracted from Humdrum files.


There are several possibilities for plotting. We will focus on the last one in the lab, but here are other possibilities:


1 Load data into a spreadsheet

You can copy-and-paste data into a spreadsheet, either Microsoft Excel, Google Spreadsheets, or similar.

In MacOS, try the command:

    humcat -s h://chorales | deg -at | serialize | ridx -H | egrep -v "=|r" | sortcount | pbcopy

pbcopy is used to copy data to the clipboard.

This will extract a count of scale-degrees in Bach chorales:

15628	5
14991	1
11710	3
10721	2 
9435	4
7761	6 
5742	7
4728	7-
1135	6+
1134	4+ 
556	3+
332	2-
326	1+
324	5+
50	3-
41	5-
32	2+
11	6-
7	1-
2	4-


Open up a spreadsheet program and paste the resulting data into the spreadsheet.


Excel-scalegrees-chorales.png

Notice that some of the cells in the B column are left justified while others are right justified. This is because Excel is autodetecting the format of each cell. It is right justifying the numbers, and left justifying the text.

Make all of the B column identified as text by clicking on the "B" at the top of the column, then right-click and choose "Format Cell..." for the context menu that appears, and choose Text as the type for the column cells:

Excel-format-cells-as-text.png

Now all cells in the B column are text:

Excel-cells-are-text.png

Switch the order of the columns and then create a bar chart:

Excel-chart1.png

Compare the to barchart created further below with pandas/jupyter:

Excel-bar-chart-jupyter.png


2 Plotting with Gnuplot

Gnuplot is a handy command-line plotting program. Here is an example of plotting the same data in gnuplot:

First save the data to a file:

          humcat -s h://chorales | deg -at | serialize | ridx -H | egrep -v "=|r" | sortcount > data.txt

On MacOS, install gnuplot with Homebrew:

         brew install gnuplot

Then create a file called plotbar with these contents:

 #!/usr/bin/env gnuplot 
 
 set terminal svg size 800,500 enhanced font "Helvetica,20"
 set output "output.svg"  
 
 set style data histogram
 set style fill solid
 set title "Scale degrees used in Bach chorales"
 
 unset key
 
 plot "data.txt" using 1:xtic(2) linecolor rgb "#ff0088"


Run the script with this command:

  chmod 0755 plotbar
  ./plotbar

This should create a file called output.svg that looks like this: