hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

sloria

The Best of the Best Practices (BOBP) Guide for Python

A "Best of the Best Practices" (BOBP) guide to developing in Python.

In General

Values

• "Build tools for others that you want to be built for you." - Kenneth Reitz
• "Simplicity is alway better than functionality." - Pieter Hintjens

mrkline

C# For Python Programmers

Syntax and core concepts

Basic Syntax

• Single-line comments are started with //. Multi-line comments are started with /* and ended with */.

• C# uses braces ({ and }) instead of indentation to organize code into blocks. If a block is a single line, the braces can be omitted. For example,

Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

jorgecarleitao

#!/usr/bin/env bash
# first argument of the script is Xapian version (e.g. 1.2.19)
VERSION=$1

# prepare
mkdir $VIRTUAL_ENV/packages && cd $VIRTUAL_ENV/packages

CORE=xapian-core-$VERSION
BINDINGS=xapian-bindings-$VERSION

xero

IRC Reference

Not intended as a guide for newbies, more like a "cheat sheet" for the somewhat experienced IRC user, especially one who wields some power over a channel.

The Basics

• /join #channel
  • Joins the specified channel.
• /part #channel
• Leaves the specified channel.

jlln

def splitDataFrameList(df,target_column,separator):
    ''' df = dataframe to split,
    target_column = the column containing the values to split
    separator = the symbol used to perform the split

    returns: a dataframe with each entry for the target column separated, with each element moved into a new row. 
    The values in the other columns are duplicated across the newly divided rows.
    '''
    def splitListToRows(row,row_accumulator,target_column,separator):
        split_row = row[target_column].split(separator)

Bekbolatov

Clean tmux cheat-sheet

By resources

sessions

list-sessions        ls         -- List sessions managed by server
new-session          new        -- Create a new session

brock

# This is just a cheat sheet:

# On production
sudo -u postgres pg_dump database | gzip -9 > database.sql.gz

# On local
scp -C production:~/database.sql.gz
dropdb database && createdb database
gunzip < database.sql.gz | psql database