SimpleCV has the ability to use macro’s built in.

If you aren’t familiar with a macro, it’s basically a way to define a set of programming events to happen with just using a single command.

In our case our macro’s will be built off the history of commands that we use in the shell. This helps us test things that work, and what doesn’t.

Remember how to load an image, find the blobs and show the image?

>>> img = Image("lenna")
>>> blobs = img.findBlobs()
>>> if blobs:

What happened there is we showed the image, but maybe we want to do that same type of functionality but for different images.

We will reduce this:

blobs = img.findBlobs()
if blobs:

To a single command like:

>>> showblobs

To do this, we can create a macro. If you type the command:

>>> history

You should get an output similiar to:

3: img = Image("lenna")
4: blobs = img.findBlobs()
if blobs:
7: _ip.magic("history ")


you can tap up or down on the arrow keys to cycle through history as well

What you can see there is all the previous commands we have ran. But in our case we want to build that into a macro. To do this we want lines 4,5, and 6 from the history, so to convert those into a macro it’s as easy as:

>>> macro showblobs 4-6

It’s just macro name lines. Then to run it you just use:

>>> showblobs

You will see the same thing as before, but now we can change the image quickly and run it again.

>>> img = Image("simplecv")
>>> showblobs

This was pretty straight forward. But say we want to change the color of the blobs shown in our macro. Then we need to use the macro If you aren’t familiar with using VI then it is recommended you read editor manual here:

To edit our existing macro we just type:

>>> edit showblobs

and you should get something similiar to:

blobs = img.findBlobs()
if blobs:

We can just edit the blobs.draw() function so it reads:

>>> blobs.draw(autocolor=True)

Press ESC Then press ** ctrl + :** Then type ** w + enter ** to save (write) the macro.

Press ESC Then press ** ctrl + :** once again, then type ** q + enter ** to quit the macro editor.

Now if you type:

>>> showblobs

You will get the image, but the blobs will be multicolored. This was just a very small intro into macros. As you can see they make writing code even faster and easier.

If you would like to learn more about macros just type:

>>> macro ?