potatowagon

Python getting started tips

• Python getting started tips
  • Common terminologies
  • Installing and switching between different python versions
    • windows py launcher
    • pyenv
      • Linux
    • conda
• useful python packages

potatowagon

import pytest 

#============ PART 1: convert str to int ==============#

def map_char_to_int(char):
    '''Maps char to int using a dict

    Args:
        char (str): a string representation of a digit eg. "1"
    Raises:

potatowagon

import pytest

'''output nth (starting from 1) sequence of fibonacci series: 0,1,1,2,3,5,8. n = 7, output = 8'''

def fib(n):
    seq = [0, 1] + [0] * (n - 2)
    for i in range(2, n):
        # dynamic programming
        seq[i] = seq[i-1] + seq[i-2]
    return seq[n-1]

potatowagon

TLDR:

os.path.join(sys.prefix, '/Lib/site-packages') on windows 

os.path.join(sys.prefix, '/Lib/site-packages') or os.path.join(sys.exec_prefix, '/Lib/site-packages') on unix

When run

setup.py install foo

potatowagon

import pytest

def escape_html(string):
    char_map = {
        "<" : "&lt",
        ">" : "&gt",
        "&" : "&amp"
    }
    out = []
    for char in string:

potatowagon

Stable vs unstable

stable: keys always remain in the same order after sorting equal values

Before:
key:0  1  2  3
   [3][0][2][2]
   
After:
key:0  1  2  3
 [0][2][2][3]

potatowagon

mapping time complexities

https://engineering.upside.com/a-beginners-guide-to-optimizing-pandas-code-for-speed-c09ef2c6a4d6

lookup time complexities

is O(1) lookup possible, like a dict, for rows with index as a unique set of values?

https://stackoverflow.com/questions/45240803/pandas-dataframe-search-is-linear-time-or-constant-time

indexing

potatowagon

try:
    from setuptools import setup
except ImportError:
    from distutils.core import setup
import re

def get_long_description():
    ''' use this if using readme for long description in pypi page'''
    with open("README.md", "r") as fh:
        readme = fh.read()

potatowagon

RTFM?

RTFM? Really? We always expect other to do that, to read the readmes we painstakingly craft to be as detailed, concise and readable as possible. As a student, Ive even had that as a lecture topic before. However, reality is people dont RTFM as much as we ideally expect them to. People are lazy. Whats the solution to that?

Prompts

I realised this from working with others. Give them a repo. Theres a readme with detailed instructions. They try to run whats in the repo. They run into all sorts of problems: forgot to run with elevated rights, did not install so and so dependencies, etc. I give them the solution, then remind them that its in the README. This repeats. Very often. Maybe I'm not doing something right. The README alone prooves to not be the most effective and user friendly form of communicating information. Why do I have to repeatedly give manual prompts? Maybe this can be automated. OH YES! PROMPTS CAN BE AUTOMATED. Infact, when designing prompts to address help mes, we realise that pro

potatowagon

Help needed: hhvm composer install hangs with no output

Soln

php /path/to/composer.phar require hhvm/hhvm-autoload

https://docs.hhvm.com/hack/getting-started/starting-a-real-project