Python IV

1. Module 'matplotlib' and its 'plot' method;
2. 'len' built-in function;
3. Reading and splitting strings from text files;
4. Formatted printing;
5. String arrays;
6. 2D arrays;
7. Descriptive statistics: mean, min, max, variance, standard deviation;
8. Histograms.

For every program you encounter it is always an excellent exercise to change the variable names to names which are most meaningful to you, then make the program run. You will gain deeper understanding of the program. You will see the program in a new light. Everyone is different: variable names most intuitive to me differ from variable names most intuitive to you. My programs are written with variable names most intuitive to me, so you should change them to names most intuitive to you so that the program flow becomes more obvious.

1. For program version #2, mark out the:
   • variable names;
   • arguments;
   • functions;
   • keywords;
   • modules;
   • methods.
2. Repeat Exercise 1 with program version #5.
3. Repeat Exercise 1 with program version #6.
4. Repeat Exercise 1 with program version #9.
5. Draw the flowchart for program version #5.
6. Draw the flowchart for program version #6.
7. Draw the flowchart for program version #9.
8. In this lesson we made multiple revisions to the program. Summarise the improvement in each version in three columns:

   version	improvement in plain English	technical modification in Python
   #1 to #2
   #2 to #3
   #3 to #4
   …
   …
   …
   #11 to #12

   version	improvement in plain English	technical modification in Python
   #13 to #14
   …
   …
   #17 to #18

1. Python keywords:
   • for
   • in
   • import
   • as
   • if
   • elif
   • else
   • and
   • or
   • return
   • with
   • as
2. Python built-in functions:
   • print(…, end='…')
   • range(…, …, …)
   • help(…)
   • dir(…)
   • int(…)
   • float(…)
   • str(…)
   • len(…)
   • range(…)
   • open(…)
3. Python modules, methods and classes:
   • random.randint(…, …)
   • matplotlib.pyplot.Circle(…, …)
   • matplotlib.pyplot.plot(…, …)
   • matplotlib.pyplot.step(…, …)
   • matplotlib.pyplot.xlabel(…), matplotlib.pyplot.ylabel(…)
   • matplotlib.pyplot.xticks(…, …, rotation='…'), matplotlib.pyplot.yticks(…, …, rotation='…')
   • matplotlib.pyplot.xlim(…), matplotlib.pyplot.ylim(…)
   • matplotlib.pyplot.legend(…)
   • matplotlib.pyplot.savefig(…)
   • fig, ax = matplotlib.pyplot.subplots(); ax.add_artist(…); fig.savefig(…),
   • numpy.floor(…), numpy.ceil(…)
   • numpy.zeros(…,dtype='…')
   • numpy.where(…)
   • numpy.arange(…)
   • numpy.histogram(…)
   • numpy.ndarray.min(…)
   • numpy.ndarray.max(…)
   • numpy.ndarray.sum(…)
   • numpy.ndarray.astype(…)
   • file.readlines(…)
   • string.split()
4. Linux commands (and options):
   • ls -l
   • wc -l
   • head
   • tail