NumPy for MATLAB users
Help
| MATLAB/Octave | Python | Description |
|---|---|---|
| doc help -i % browse with Info |
help() | Browse help interactively |
| help help or doc doc | help | Help on using help |
| help plot | help(plot) or ?plot | Help for a function |
| help splines or doc splines | help(pylab) | Help for a toolbox/library package |
| demo | Demonstration examples |
Searching available documentation
| MATLAB/Octave | Python | Description |
|---|---|---|
| lookfor plot | Search help files | |
| help | help(); modules [Numeric] | List available packages |
| which plot | help(plot) | Locate functions |
Using interactively
| MATLAB/Octave | Python | Description |
|---|---|---|
| octave -q | ipython -pylab | Start session |
| TAB or M-? | TAB | Auto completion |
| foo(.m) | execfile('foo.py') or run foo.py | Run code from file |
| history | hist -n | Command history |
| diary on [..] diary off | Save command history | |
| exit or quit | CTRL-D CTRL-Z # windows sys.exit() |
End session |
Operators
| MATLAB/Octave | Python | Description |
|---|---|---|
| help - | Help on operator syntax |
Arithmetic operators
| MATLAB/Octave | Python | Description |
|---|---|---|
| a=1; b=2; | a=1; b=1 | Assignment; defining a number |
| a + b | a + b or add(a,b) | Addition |
| a - b | a - b or subtract(a,b) | Subtraction |
| a * b | a * b or multiply(a,b) | Multiplication |
| a / b | a / b or divide(a,b) | Division |
| a .^ b | a ** b power(a,b) pow(a,b) |
Power, $a^b$ |
| rem(a,b) | a % b remainder(a,b) fmod(a,b) |
Remainder |
| a+=1 | a+=b or add(a,b,a) | In place operation to save array creation overhead |
| factorial(a) | Factorial, $n!$ |
Relational operators
| MATLAB/Octave | Python | Description |
|---|---|---|
| a == b | a == b or equal(a,b) | Equal |
| a < b | a < b or less(a,b) | Less than |
| a > b | a > b or greater(a,b) | Greater than |
| a <= b | a <= b or less_equal(a,b) | Less than or equal |
| a >= b | a >= b or greater_equal(a,b) | Greater than or equal |
| a ~= b | a != b or not_equal(a,b) | Not Equal |
Logical operators
| MATLAB/Octave | Python | Description |
|---|---|---|
| a && b | a and b | Short-circuit logical AND |
| a || b | a or b | Short-circuit logical OR |
| a & b or and(a,b) | logical_and(a,b) or a and b | Element-wise logical AND |
| a | b or or(a,b) | logical_or(a,b) or a or b | Element-wise logical OR |
| xor(a, b) | logical_xor(a,b) | Logical EXCLUSIVE OR |
| ~a or not(a) ~a or !a |
logical_not(a) or not a | Logical NOT |
| any(a) | True if any element is nonzero | |
| all(a) | True if all elements are nonzero |
root and logarithm
| MATLAB/Octave | Python | Description |
|---|---|---|
| sqrt(a) | math.sqrt(a) | Square root |
| log(a) | math.log(a) | Logarithm, base $e$ (natural) |
| log10(a) | math.log10(a) | Logarithm, base 10 |
| log2(a) | math.log(a, 2) | Logarithm, base 2 (binary) |
| exp(a) | math.exp(a) | Exponential function |
Round off
| MATLAB/Octave | Python | Description |
|---|---|---|
| round(a) | around(a) or math.round(a) | Round |
| ceil(a) | ceil(a) | Round up |
| floor(a) | floor(a) | Round down |
| fix(a) | fix(a) | Round towards zero |
Mathematical constants
| MATLAB/Octave | Python | Description |
|---|---|---|
| pi | math.pi | $\pi=3.141592$ |
| exp(1) | math.e or math.exp(1) | $e=2.718281$ |
Missing values; IEEE-754 floating point status flags
| MATLAB/Octave | Python | Description |
|---|---|---|
| NaN | nan | Not a Number |
| Inf | inf | Infinity, $\infty$ |
| plus_inf | Infinity, $+\infty$ | |
| minus_inf | Infinity, $-\infty$ | |
| plus_zero | Plus zero, $+0$ | |
| minus_zero | Minus zero, $-0$ |
Complex numbers
| MATLAB/Octave | Python | Description |
|---|---|---|
| i | z = 1j | Imaginary unit |
| z = 3+4i | z = 3+4j or z = complex(3,4) | A complex number, $3+4i$ |
| abs(z) | abs(3+4j) | Absolute value (modulus) |
| real(z) | z.real | Real part |
| imag(z) | z.imag | Imaginary part |
| arg(z) | Argument | |
| conj(z) | z.conj(); z.conjugate() | Complex conjugate |
Trigonometry
| MATLAB/Octave | Python | Description |
|---|---|---|
| atan(a,b) | atan2(b,a) | Arctangent, $\arctan(b/a)$ |
| hypot(x,y) | Hypotenus; Euclidean distance |
Generate random numbers
| MATLAB/Octave | Python | Description |
|---|---|---|
| rand(1,10) | random.random((10,)) random.uniform((10,)) |
Uniform distribution |
| 2+5*rand(1,10) | random.uniform(2,7,(10,)) | Uniform: Numbers between 2 and 7 |
| rand(6) | random.uniform(0,1,(6,6)) | Uniform: 6,6 array |
| randn(1,10) | random.standard_normal((10,)) | Normal distribution |
Vectors
| MATLAB/Octave | Python | Description |
|---|---|---|
| a=[2 3 4 5]; | a=array([2,3,4,5]) | Row vector, $1 \times n$-matrix |
| adash=[2 3 4 5]'; | array([2,3,4,5])[:,NewAxis] array([2,3,4,5]).reshape(-1,1) r_[1:10,'c'] |
Column vector, $m \times 1$-matrix |
Sequences
| MATLAB/Octave | Python | Description |
|---|---|---|
| 1:10 | arange(1,11, dtype=Float) range(1,11) |
1,2,3, ... ,10 |
| 0:9 | arange(10.) | 0.0,1.0,2.0, ... ,9.0 |
| 1:3:10 | arange(1,11,3) | 1,4,7,10 |
| 10:-1:1 | arange(10,0,-1) | 10,9,8, ... ,1 |
| 10:-3:1 | arange(10,0,-3) | 10,7,4,1 |
| linspace(1,10,7) | linspace(1,10,7) | Linearly spaced vector of n=7 points |
| reverse(a) | a[::-1] or | Reverse |
| a(:) = 3 | a.fill(3), a[:] = 3 | Set all values to same scalar value |
Concatenation (vectors)
| MATLAB/Octave | Python | Description |
|---|---|---|
| [a a] | concatenate((a,a)) | Concatenate two vectors |
| [1:4 a] | concatenate((range(1,5),a), axis=1) |
Repeating
| MATLAB/Octave | Python | Description |
|---|---|---|
| [a a] | concatenate((a,a)) | 1 2 3, 1 2 3 |
| a.repeat(3) or | 1 1 1, 2 2 2, 3 3 3 | |
| a.repeat(a) or | 1, 2 2, 3 3 3 |
Miss those elements out
| MATLAB/Octave | Python | Description |
|---|---|---|
| a(2:end) | a[1:] | miss the first element |
| a([1:9]) | miss the tenth element | |
| a(end) | a[-1] | last element |
| a(end-1:end) | a[-2:] | last two elements |
Maximum and minimum
| MATLAB/Octave | Python | Description |
|---|---|---|
| max(a,b) | maximum(a,b) | pairwise max |
| max([a b]) | concatenate((a,b)).max() | max of all values in two vectors |
| [v,i] = max(a) | v,i = a.max(0),a.argmax(0) |
Vector multiplication
| MATLAB/Octave | Python | Description |
|---|---|---|
| a.*a | a*a | Multiply two vectors |
| dot(u,v) | dot(u,v) | Vector dot product, $u \cdot v$ |
Matrices
| MATLAB/Octave | Python | Description |
|---|---|---|
| a = [2 3;4 5] | a = array([[2,3],[4,5]]) | Define a matrix |
Concatenation (matrices); rbind and cbind
| MATLAB/Octave | Python | Description |
|---|---|---|
| [a ; b] | concatenate((a,b), axis=0) vstack((a,b)) |
Bind rows |
| [a , b] | concatenate((a,b), axis=1) hstack((a,b)) |
Bind columns |
| concatenate((a,b), axis=2) dstack((a,b)) |
Bind slices (three-way arrays) | |
| [a(:), b(:)] | concatenate((a,b), axis=None) | Concatenate matrices into one vector |
| [1:4 ; 1:4] | concatenate((r_[1:5],r_[1:5])).reshape(2,-1) vstack((r_[1:5],r_[1:5])) |
Bind rows (from vectors) |
| [1:4 ; 1:4]' | Bind columns (from vectors) |
Array creation
| MATLAB/Octave | Python | Description |
|---|---|---|
| zeros(3,5) | zeros((3,5),Float) | 0 filled array |
| zeros((3,5)) | 0 filled array of integers | |
| ones(3,5) | ones((3,5),Float) | 1 filled array |
| ones(3,5)*9 | Any number filled array | |
| eye(3) | identity(3) | Identity matrix |
| diag([4 5 6]) | diag((4,5,6)) | Diagonal |
| magic(3) | Magic squares; Lo Shu | |
| a = empty((3,3)) | Empty array |
Reshape and flatten matrices
| MATLAB/Octave | Python | Description |
|---|---|---|
| reshape(1:6,3,2)'; | arange(1,7).reshape(2,-1) a.setshape(2,3) |
Reshaping (rows first) |
| reshape(1:6,2,3); | arange(1,7).reshape(-1,2).transpose() | Reshaping (columns first) |
| a'(:) | a.flatten() or | Flatten to vector (by rows, like comics) |
| a(:) | a.flatten(1) | Flatten to vector (by columns) |
| vech(a) | Flatten upper triangle (by columns) |
Shared data (slicing)
| MATLAB/Octave | Python | Description |
|---|---|---|
| b = a | b = a.copy() | Copy of a |
Indexing and accessing elements (Python: slicing)
| MATLAB/Octave | Python | Description |
|---|---|---|
| a = [ 11 12 13 14 ... 21 22 23 24 ... 31 32 33 34 ] |
a = array([[ 11, 12, 13, 14 ], [ 21, 22, 23, 24 ], [ 31, 32, 33, 34 ]]) |
Input is a 3,4 array |
| a(2,3) | a[1,2] | Element 2,3 (row,col) |
| a(1,:) | a[0,] | First row |
| a(:,1) | a[:,0] | First column |
| a([1 3],[1 4]); | a.take([0,2]).take([0,3], axis=1) | Array as indices |
| a(2:end,:) | a[1:,] | All, except first row |
| a(end-1:end,:) | a[-2:,] | Last two rows |
| a(1:2:end,:) | a[::2,:] | Strides: Every other row |
| a[...,2] | Third in last dimension (axis) | |
| a(:,[1 3 4]) | a.take([0,2,3],axis=1) | Remove one column |
| a.diagonal(offset=0) | Diagonal |
Assignment
| MATLAB/Octave | Python | Description |
|---|---|---|
| a(:,1) = 99 | a[:,0] = 99 | |
| a(:,1) = [99 98 97]' | a[:,0] = array([99,98,97]) | |
| a(a>90) = 90; | (a>90).choose(a,90) a.clip(min=None, max=90) |
Clipping: Replace all elements over 90 |
| a.clip(min=2, max=5) | Clip upper and lower values |
Transpose and inverse
| MATLAB/Octave | Python | Description |
|---|---|---|
| a' | a.conj().transpose() | Transpose |
| a.' or transpose(a) | a.transpose() | Non-conjugate transpose |
| det(a) | linalg.det(a) or | Determinant |
| inv(a) | linalg.inv(a) or | Inverse |
| pinv(a) | linalg.pinv(a) | Pseudo-inverse |
| norm(a) | norm(a) | Norms |
| eig(a) | linalg.eig(a)[0] | Eigenvalues |
| svd(a) | linalg.svd(a) | Singular values |
| chol(a) | linalg.cholesky(a) | Cholesky factorization |
| [v,l] = eig(a) | linalg.eig(a)[1] | Eigenvectors |
| rank(a) | rank(a) | Rank |
Sum
| MATLAB/Octave | Python | Description |
|---|---|---|
| sum(a) | a.sum(axis=0) | Sum of each column |
| sum(a') | a.sum(axis=1) | Sum of each row |
| sum(sum(a)) | a.sum() | Sum of all elements |
| a.trace(offset=0) | Sum along diagonal | |
| cumsum(a) | a.cumsum(axis=0) | Cumulative sum (columns) |
Sorting
| MATLAB/Octave | Python | Description |
|---|---|---|
| a = [ 4 3 2 ; 2 8 6 ; 1 4 7 ] | a = array([[4,3,2],[2,8,6],[1,4,7]]) | Example data |
| sort(a(:)) | a.ravel().sort() or | Flat and sorted |
| sort(a) | a.sort(axis=0) or msort(a) | Sort each column |
| sort(a')' | a.sort(axis=1) | Sort each row |
| sortrows(a,1) | a[a[:,0].argsort(),] | Sort rows (by first row) |
| a.ravel().argsort() | Sort, return indices | |
| a.argsort(axis=0) | Sort each column, return indices | |
| a.argsort(axis=1) | Sort each row, return indices |
Maximum and minimum
| MATLAB/Octave | Python | Description |
|---|---|---|
| max(a) | a.max(0) or amax(a [,axis=0]) | max in each column |
| max(a') | a.max(1) or amax(a, axis=1) | max in each row |
| max(max(a)) | a.max() or | max in array |
| [v i] = max(a) | return indices, i | |
| max(b,c) | maximum(b,c) | pairwise max |
| cummax(a) | ||
| a.ptp(); a.ptp(0) | max-to-min range |
Matrix manipulation
| MATLAB/Octave | Python | Description |
|---|---|---|
| fliplr(a) | fliplr(a) or a[:,::-1] | Flip left-right |
| flipud(a) | flipud(a) or a[::-1,] | Flip up-down |
| rot90(a) | rot90(a) | Rotate 90 degrees |
| repmat(a,2,3) kron(ones(2,3),a) |
kron(ones((2,3)),a) | Repeat matrix: [ a a a ; a a a ] |
| triu(a) | triu(a) | Triangular, upper |
| tril(a) | tril(a) | Triangular, lower |
Equivalents to "size"
| MATLAB/Octave | Python | Description |
|---|---|---|
| size(a) | a.shape or a.getshape() | Matrix dimensions |
| size(a,2) or length(a) | a.shape[1] or size(a, axis=1) | Number of columns |
| length(a(:)) | a.size or size(a[, axis=None]) | Number of elements |
| ndims(a) | a.ndim | Number of dimensions |
| a.nbytes | Number of bytes used in memory |
Matrix- and elementwise- multiplication
| MATLAB/Octave | Python | Description |
|---|---|---|
| a .* b | a * b or multiply(a,b) | Elementwise operations |
| a * b | matrixmultiply(a,b) | Matrix product (dot product) |
| inner(a,b) or | Inner matrix vector multiplication $a\cdot b'$ | |
| outer(a,b) or | Outer product | |
| kron(a,b) | kron(a,b) | Kronecker product |
| a / b | Matrix division, $b{\cdot}a^{-1}$ | |
| a \ b | linalg.solve(a,b) | Left matrix division, $b^{-1}{\cdot}a$ \newline (solve linear equations) |
| vdot(a,b) | Vector dot product | |
| cross(a,b) | Cross product |
Find; conditional indexing
| MATLAB/Octave | Python | Description |
|---|---|---|
| find(a) | a.ravel().nonzero() | Non-zero elements, indices |
| [i j] = find(a) | (i,j) = a.nonzero() (i,j) = where(a!=0) |
Non-zero elements, array indices |
| [i j v] = find(a) | v = a.compress((a!=0).flat) v = extract(a!=0,a) |
Vector of non-zero values |
| find(a>5.5) | (a>5.5).nonzero() | Condition, indices |
| a.compress((a>5.5).flat) | Return values | |
| a .* (a>5.5) | where(a>5.5,0,a) or a * (a>5.5) | Zero out elements above 5.5 |
| a.put(2,indices) | Replace values |
Multi-way arrays
| MATLAB/Octave | Python | Description |
|---|---|---|
| a = cat(3, [1 2; 1 2],[3 4; 3 4]); | a = array([[[1,2],[1,2]], [[3,4],[3,4]]]) | Define a 3-way array |
| a(1,:,:) | a[0,...] |
File input and output
| MATLAB/Octave | Python | Description |
|---|---|---|
| f = load('data.txt') | f = fromfile("data.txt") f = load("data.txt") |
Reading from a file (2d) |
| f = load('data.txt') | f = load("data.txt") | Reading from a file (2d) |
| x = dlmread('data.csv', ';') | f = load('data.csv', delimiter=';') | Reading fram a CSV file (2d) |
| save -ascii data.txt f | save('data.csv', f, fmt='%.6f', delimiter=';') | Writing to a file (2d) |
| f.tofile(file='data.csv', format='%.6f', sep=';') | Writing to a file (1d) | |
| f = fromfile(file='data.csv', sep=';') | Reading from a file (1d) |
Plotting
Basic x-y plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| plot(a) | plot(a) | 1d line plot |
| plot(x(:,1),x(:,2),'o') | plot(x[:,0],x[:,1],'o') | 2d scatter plot |
| plot(x1,y1, x2,y2) | plot(x1,y1,'bo', x2,y2,'go') | Two graphs in one plot |
| plot(x1,y1) hold on plot(x2,y2) |
plot(x1,y1,'o') plot(x2,y2,'o') show() # as normal |
Overplotting: Add new plots to current |
| subplot(211) | subplot(211) | subplots |
| plot(x,y,'ro-') | plot(x,y,'ro-') | Plotting symbols and color |
Axes and titles
| MATLAB/Octave | Python | Description |
|---|---|---|
| grid on | grid() | Turn on grid lines |
| axis equal axis('equal') replot |
figure(figsize=(6,6)) | 1:1 aspect ratio |
| axis([ 0 10 0 5 ]) | axis([ 0, 10, 0, 5 ]) | Set axes manually |
| title('title') xlabel('x-axis') ylabel('y-axis') |
Axis labels and titles | |
| text(2,25,'hello') | Insert text |
Log plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| semilogy(a) | semilogy(a) | logarithmic y-axis |
| semilogx(a) | semilogx(a) | logarithmic x-axis |
| loglog(a) | loglog(a) | logarithmic x and y axes |
Filled plots and bar plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| fill(t,s,'b', t,c,'g') % fill has a bug? |
fill(t,s,'b', t,c,'g', alpha=0.2) | Filled plot |
Functions
| MATLAB/Octave | Python | Description |
|---|---|---|
| f = inline('sin(x/3) - cos(x/5)') | Defining functions | |
| ezplot(f,[0,40]) fplot('sin(x/3) - cos(x/5)',[0,40]) % no ezplot |
x = arrayrange(0,40,.5) y = sin(x/3) - cos(x/5) plot(x,y, 'o') |
Plot a function for given range |
Polar plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| theta = 0:.001:2*pi; r = sin(2*theta); |
theta = arange(0,2*pi,0.001) r = sin(2*theta) |
|
| polar(theta, rho) | polar(theta, rho) |
Histogram plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| hist(randn(1000,1)) | ||
| hist(randn(1000,1), -4:4) | ||
| plot(sort(a)) |
3d data
Contour and image plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| contour(z) | levels, colls = contour(Z, V, origin='lower', extent=(-3,3,-3,3)) clabel(colls, levels, inline=1, fmt='%1.1f', fontsize=10) |
Contour plot |
| contourf(z); colormap(gray) | contourf(Z, V, cmap=cm.gray, origin='lower', extent=(-3,3,-3,3)) |
Filled contour plot |
| image(z) colormap(gray) |
im = imshow(Z, interpolation='bilinear', origin='lower', extent=(-3,3,-3,3)) |
Plot image data |
| # imshow() and contour() as above | Image with contours | |
| quiver() | quiver() | Direction field vectors |
Perspective plots of surfaces over the x-y plane
| MATLAB/Octave | Python | Description |
|---|---|---|
| n=-2:.1:2; [x,y] = meshgrid(n,n); z=x.*exp(-x.^2-y.^2); |
n=arrayrange(-2,2,.1) [x,y] = meshgrid(n,n) z = x*power(math.e,-x**2-y**2) |
|
| mesh(z) | Mesh plot | |
| surf(x,y,z) or surfl(x,y,z) % no surfl() |
Surface plot |
Scatter (cloud) plots
| MATLAB/Octave | Python | Description |
|---|---|---|
| plot3(x,y,z,'k+') | 3d scatter plot |
Save plot to a graphics file
| MATLAB/Octave | Python | Description |
|---|---|---|
| plot(1:10) print -depsc2 foo.eps gset output "foo.eps" gset terminal postscript eps plot(1:10) |
savefig('foo.eps') | PostScript |
| savefig('foo.pdf') | ||
| savefig('foo.svg') | SVG (vector graphics for www) | |
| print -dpng foo.png | savefig('foo.png') | PNG (raster graphics) |
Data analysis
Set membership operators
| MATLAB/Octave | Python | Description |
|---|---|---|
| a = [ 1 2 2 5 2 ]; b = [ 2 3 4 ]; |
a = array([1,2,2,5,2]) b = array([2,3,4]) a = set([1,2,2,5,2]) b = set([2,3,4]) |
Create sets |
| unique(a) | unique1d(a) unique(a) set(a) |
Set unique |
| union(a,b) | union1d(a,b) a.union(b) |
Set union |
| intersect(a,b) | intersect1d(a) a.intersection(b) |
Set intersection |
| setdiff(a,b) | setdiff1d(a,b) a.difference(b) |
Set difference |
| setxor(a,b) | setxor1d(a,b) a.symmetric_difference(b) |
Set exclusion |
| ismember(2,a) | 2 in a setmember1d(2,a) contains(a,2) |
True for set member |
Statistics
| MATLAB/Octave | Python | Description |
|---|---|---|
| mean(a) | a.mean(axis=0) mean(a [,axis=0]) |
Average |
| median(a) | median(a) or median(a [,axis=0]) | Median |
| std(a) | a.std(axis=0) or std(a [,axis=0]) | Standard deviation |
| var(a) | a.var(axis=0) or var(a) | Variance |
| corr(x,y) | correlate(x,y) or corrcoef(x,y) | Correlation coefficient |
| cov(x,y) | cov(x,y) | Covariance |
Interpolation and regression
| MATLAB/Octave | Python | Description |
|---|---|---|
| z = polyval(polyfit(x,y,1),x) plot(x,y,'o', x,z ,'-') |
(a,b) = polyfit(x,y,1) plot(x,y,'o', x,a*x+b,'-') |
Straight line fit |
| a = x\y | linalg.lstsq(x,y) | Linear least squares $y = ax + b$ |
| polyfit(x,y,3) | polyfit(x,y,3) | Polynomial fit |
Non-linear methods
Polynomials, root finding
| MATLAB/Octave | Python | Description |
|---|---|---|
| poly() | Polynomial | |
| roots([1 -1 -1]) | roots() | Find zeros of polynomial |
| f = inline('1/x - (x-1)') fzero(f,1) |
Find a zero near $x = 1$ | |
| solve('1/x = x-1') | Solve symbolic equations | |
| polyval([1 2 1 2],1:10) | polyval(array([1,2,1,2]),arange(1,11)) | Evaluate polynomial |
Differential equations
| MATLAB/Octave | Python | Description |
|---|---|---|
| diff(a) | diff(x, n=1, axis=0) | Discrete difference function and approximate derivative |
| Solve differential equations |
Fourier analysis
| MATLAB/Octave | Python | Description |
|---|---|---|
| fft(a) | fft(a) or | Fast fourier transform |
| ifft(a) | ifft(a) or | Inverse fourier transform |
| convolve(x,y) | Linear convolution |
Symbolic algebra; calculus
| MATLAB/Octave | Python | Description |
|---|---|---|
| factor() | Factorization |
Programming
| MATLAB/Octave | Python | Description |
|---|---|---|
| .m | .py | Script file extension |
| % % or # |
# | Comment symbol (rest of line) |
| % must be in MATLABPATH % must be in LOADPATH |
from pylab import * | Import library functions |
| string='a=234'; eval(string) |
string="a=234" eval(string) |
Eval |
Loops
| MATLAB/Octave | Python | Description |
|---|---|---|
| for i=1:5; disp(i); end | for i in range(1,6): print(i) | for-statement |
| for i=1:5 disp(i) disp(i*2) end |
for i in range(1,6): print(i) print(i*2) |
Multiline for statements |
Conditionals
| MATLAB/Octave | Python | Description |
|---|---|---|
| if 1>0 a=100; end | if 1>0: a=100 | if-statement |
| if 1>0 a=100; else a=0; end | if-else-statement |
Debugging
| MATLAB/Octave | Python | Description |
|---|---|---|
| ans | Most recent evaluated expression | |
| whos or who | List variables loaded into memory | |
| clear x or clear [all] | Clear variable $x$ from memory | |
| disp(a) | print a |
Working directory and OS
| MATLAB/Octave | Python | Description |
|---|---|---|
| dir or ls | os.listdir(".") | List files in directory |
| what | grep.grep("*.py") | List script files in directory |
| pwd | os.getcwd() | Displays the current working directory |
| cd foo | os.chdir('foo') | Change working directory |
| !notepad system("notepad") |
os.system('notepad') os.popen('notepad') |
Invoke a System Command |
by 1957
