within python venv, can use "deactivate" to leave to delete a venv, just delete the folder.
python: + pyenv and pipenv should be separate 01-00 and 02-00. for each have subsection on + installing the package + creating envs + exiting + listing + deleting + installing packages inside
python: itertools
for _ in range + means that we don’t care about how many times it has run so far, don’t get i to play with + can still do print(_) though
r strings . raw strings. r"hello" don’t need to eg escape backslashes
super() function around classes
flask (web dev thing)
str and repr
"is" keyword
can do currying stuff with base python? writing curried functions with nested currying existing functions currying with def function; currying with lambda functions
functions stuff: if function parameter has mutable default, might not work on repeated calls? eg
def my_function(my_parameter = []):
my_parameter.append(1)
print(my_parameter)each time will print larger list
can create partial functions using lambdas sum=lambda x, y: x+y incr = lambda y: sum(1,y)
scope: can access variables in outer scope, but not change them? declare global x inside function to change global a=1
similarly, nonlocal declaration can be used to access variables from outer function
build ins: map filter reduce
meaning of * prefix eg function call * and ** prefix for args means split up v in *v and pass each as parameter print(v) prints the list print(*v) same as print(v[0], v[1], v[2],...) double ** prefix similar but for dict
factories (design pattern for classes)
composites and components design pattern, can be used instead of inheritance in some cases create an instance of another class from within a class. then can use methods etc associated with that class
classes: can get type of object with
type(obj)
obj.__class__type of base classes is "type" type of type is type
base classes are int, float, dict, list, tuple, type
metaclass: + classes normally are based on type + we can instead use another class, a metaclass. can then overwrite eg __new__. + different to regular inheritnace, doesn’t look to metaclass for methods etc
class MyClass(metaclass=my_metaclass):functools
def my_function(a,b,c):
return a+b+c
functools.partial(my_function,1)datetime. also have time, calendar. time has time.perf_counter. better for measuring performance than time.time
logging module
typing (can do additional static analysis) Protocol is part of typing module
import x looks for x in sys.path
abstract base class (ABC) module abstract methods (part of abc)
python -m ast to get abstract syntax tree can also do "import ast"
pipx + allows for applications to be distributed + uses same python binary as installed?
"poetry"? package manager??
package creation stuff? + distutils and setup.py and setup.cfg + pyproject.toml
python data: engineering pipelines using apache airflow (python specific)
more packages related to pandas pandera dask modin PySpark dataframe vaex
pytorch: transfomer; lstm; convolution pytorch stuff pytorch.nn.Sequential (stack layers together) nn.Linear(a,b) nn.ReLU() nn.Sigmoid()
nn.Module() (class, can inherit from it, has methods)
torch.optim torch.optim.Adam()
can define loss functions nn.BCELoss (binary cross entropy)
arr.np.array([1,2,3]) can create views and copies x = arr.view() y = arr.copy() chaning x changes arr, changing y doesn’t change arr
can check with x.base, y.base, arr.base returns none if not a view
note that no () at end.
numpy: difference between view and copy numpy data types. NaN only float, not int? does numpy support int?
can do the base copy view checks for can do for series too, as in numpy data types in pandas, inc objects
concepts of missing data in pandas. different approaches, what role None and NaN play, also NaT, NASA shift on pandas
page on pandas: + loc, iloc, selection with brackets, at, iat (at and iat are for elecemnts, loc and iloc for sub df). loc and at work on named index, iat and iloc on index offset? is that right?. df._is_copy df._is_view
h3 on econ modules? + quantecon + dynare
pystan in python
page on mpmath (arbitrarily accurate numbers)
page on sympy (depends on mpmath)