Grid Printer Exercise
Printing a Grid
(adapted from Downey, “Think Python”, ex. 3.5)
Goal:
Write a function that draws a grid like the following:
+ - - - - + - - - - +
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+ - - - - + - - - - +
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+ - - - - + - - - - +
Hints
A couple features to get you started…
printing
To print more than one value on a line, you can pass multiple names into the print function:
print('+', '-')
If you don’t want a newline after something is printed, you tell Python what you want the print to end with like so:
print('+', end=' ')
print('-')
The output of these statements is '+ -'.
(that end parameter defaults to a newline…)
no arguments
A print function with no arguments ends the current line and goes to the next line:
print()
simply prints and empty line.
Simple string manipulation:
You can put two strings together with the plus operator:
In [20]: "this" + "that"
Out[20]: 'thisthat
This is called concatenation.
Concatenation is particularly useful if the strings have been assigned names:
In [21]: plus = '+'
In [22]: minus = '-'
In [23]: plus + minus + plus
Out[23]: '+-+'
Note that you can link any number of operations together in an expression.
Multiplication of strings
You can also multiply strings:
In [24]: '+' * 10
Out[24]: '++++++++++'
And combine that with plus in a complex expression:
In [29]: first_name = 'Chris'
In [30]: last_name = 'Barker'
In [31]: 5 * '*' + first_name +' ' + last_name + 5 * '*'
Out[31]: '*****Chris Barker*****'
Note that there are better ways to build up complex strings – we’ll get to that later.
Now you’ve got what you need to print that grid…
** give it a try! **
Part 2
Making it more general.
Make it a function
One of the points of writing functions is so you can write code that does similar things, but customized by the values of input parameters. So what if we want to be able to print that grid at an arbitrary size?
Write a function print_grid(n) that takes one integer argument and prints a grid just like before, BUT the size of the grid is given by the argument.
For example, print_grid(9) prints the grid at the top of this page.
print_grid(3) would print a smaller grid:
+ - + - +
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+ - + - +
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+ - + - +
print_grid(15) prints a larger grid:
+ - - - - - - - + - - - - - - - +
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+ - - - - - - - + - - - - - - - +
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+ - - - - - - - + - - - - - - - +
This problem is underspecified. Do something reasonable.
Part 3:
Even more general…
A function with two parameters
Write a function that draws a similar grid with a specified number of rows and columns, and with each cell a given size.
For example, print_grid2(3,4) results in:
+ - - - - + - - - - + - - - - +
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+ - - - - + - - - - + - - - - +
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+ - - - - + - - - - + - - - - +
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+ - - - - + - - - - + - - - - +
(three rows, three columns, and each grid cell four “units” in size)
What to do about rounding? – you decide.
Another example: print_grid2(5,3):
+ - - - + - - - + - - - + - - - + - - - +
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+ - - - + - - - + - - - + - - - + - - - +
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+ - - - + - - - + - - - + - - - + - - - +
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+ - - - + - - - + - - - + - - - + - - - +
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+ - - - + - - - + - - - + - - - + - - - +
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+ - - - + - - - + - - - + - - - + - - - +
Have fun!