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diff --git a/plotting-files.org b/plotting-files.org deleted file mode 100644 index c8e5964..0000000 --- a/plotting-files.org +++ /dev/null @@ -1,109 +0,0 @@ -* Plotting Experimental Data -*** Outline -***** Introduction -******* Why do we want to do that? -******* Inputting data -********* Lists -********* Files -******* Arsenal Required -********* Lists -*********** initializing -*********** appending to lists -********* for loops -*********** iterating over a list -********* basic plotting -***** Inputting data as lists -******* Input the dependent and independent variables in two lists -******* Plot the points -***** Plotting from files -******* Look at the file -******* Read the file and get data into variables -******* Do any massaging required -******* Plot the points - -*** Script - -This video will teach you how to plot experimental data, with two -variables. - -In general, we don't plot (analytical) functions. We often have -experimental data points, that we wish to plot. We shall look at -inputting this data and plotting it. - -The data could be input (or entered) in two formats. For smaller data -sets we could use lists to input the data and use plain text files for -(somewhat?) larger ones. (Binary files?) - -[[[Before starting with this video, you should be comfortable with - - Lists - - initializing them - - appending elements to lists - - for command - - iterating over a list - - split command - - plot command - - plotting two variables -]]] - -Let's begin with inputting the data as lists and plotting it. - -x = [0, 1, 2.1, 3.1, 4.2, 5.2] -y = [0, 0.8, 0.9, 0, -0.9, -0.8] -Now we have two lists x and y, with the values that we wish to plot. - -We say: -plot (x, y, 'o') - -and there, we have our plot! - -[We close the plot window. ] - -Now, that we know how to plot data which is in lists, we will look at -plotting data which is in a text file. Essentially, we read the data -from the file and massage it into lists again. Then we can easily -plot it, as we already did. - -As an example we will use the data collected from a simple pendulum -experiment. We have the data of, the length of pendulum vs. the time -period of the pendulum in the file pendulum.txt - -In []: cat pendulum.txt (windows?) - -The cat command, shows the contents of the file. - -The first column is the length of the pendulum and the second column -is the time. We read the file line-by-line, collect the data into -lists and plot them. - -We begin with initializing three empty lists for length, time-period -and square of the time-period. - -l = [] -t = [] -tsq = [] - -Now we open the file and read it line by line. -for line in open('pendulum.txt'): - -We split each line at the space - point = line.split() - -Then we append the length and time values to the corresponding -lists. Note that they are converted from strings to floats, before -appending to the lists - l.append(float(point[0]) - t.append(float(point[1]) -We also calculate the squares of the time-period and append to the end -of the tsq list. - tsq.append(t[-1]*t[-1]) -As you might be aware, t[-1] gives the last element of the list t. - -Now the lists l, t have the required data. We can simply plot them, as -we did already. - -plot(l, t, 'o') - -Enjoy! - -*** Notes - - Also put in code snippets? |