Charting daily balance
Using % for string formatting is deprecated, you should be using str.format instead. The str.format methods also allows you to do some cool things as well. Here's an example of it in action:

# No positional or named arguments
print "{} {}".format("Hello", "world")

# Positional arguments (*args)
print "{1} {0}".format("world", "Hello")

# Named arguments (**kwargs)
print "{word1} {word2}".format(word1="Hello", word2="world")


When running the line Tk.mainloop(), you should encapsulate it in an if __name__ == "__main__": block. See this Stackoverflow question for more details.

These two lines should be moved underneath all of your imports/includes:


matplotlib.rcParams['toolbar'] = 'None'
matplotlib.use('TkAgg')



I'm also noticing your lack of comments as well. Even if this is a small utility script, I'd still recommend adding comments for clarity.

Finally, a few of your variable names confuse me. For example, f, a, and j are all good examples of names that could be better. Try seeing if you can expand on these.