Transitioning from MATLAB¶

Differences Between Python and MATLAB¶

Indentation¶

Python interprets your code based off of the amount of indentation, or “whitespace”, each line has. Successive lines with the same indentation are recognized as code blocks, which are run in context of the header:

# Good indentation
if(x == y):       # Header
    x = x * 2     # Code block
    x = x + y     # Code block
    return x      # Code block

# Bad indentation
if(x == y):
   x = x * 2
     x = x + y
    return x

Ending statements¶

Unlike MATLAB, you do not need a semi-colon to end a statement in Python.

Data indexing¶

MATLAB matrices begin at index 1, whereas Python lists begin at index 0.

>>> list = ['dog', 'cat', 'fish']
>>> list[0]
dog

Functions¶

In MATLAB, functions are written with the keyword function, the return parameter(s), the equals sign =, the function name, and the input parameters. Functions are terminated with end.

function y = average(x)
    if ~isvector(x)
        error('Input must be a vector')
    end
    y = sum(x)/length(x);
end

In Python, functions can be written by using the keyword def, followed by the function name, the input parameters in parentheses, and a colon. You may return a value at the end, although it isn’t necessary.

def average(x):
    if ~isvector(x)
        raise VocationError("Input must be a vector")
    return sum(x)/length(x)

Statements¶

for loops and if statements do not require the keyword “end” in Python. The loop header in MATLAB varies from that of Python. Check examples below:

% MATLAB
s = 10;
H = zeros(s);
for c = 1:s
    for r = 1:s
        H(r,c) = 1/(r+c-1);
    end
end

# Python
s = 10
H = []
for (r in range(s)):
    for (c in range(s)):
        H[r][c].append(1/(r + c - 1))

Printing¶

In Python, printing is done with print(), whereas MATLAB uses disp().