nadavrot

High-Performance Matrix Multiplication

This is a short post that explains how to write a high-performance matrix multiplication program on modern processors. In this tutorial I will use a single core of the Skylake-client CPU with AVX2, but the principles in this post also apply to other processors with different instruction sets (such as AVX512).

Intro

Matrix multiplication is a mathematical operation that defines the product of

scf37

Simulate a scanned PDF with ImageMagick

1. Download and install Ghostscript and ImageMagick + Convert Module
2. Execute the following command in the console (change the filename)

$ convert -density 200 INPUT.pdf -rotate 0.3 +noise Multiplicative -format pdf  -quality 85 -compress JPEG -colorspace gray OUTPUT.pdf

Description of the options

• -density: set the input DPI to 200
• -rotate: set Page rotation to 0.3 degrees

CliffordAnderson

Analyzing the U-Bahn Network with Neo4J

The goal of this exercise is to extract information about the Berlin metro system from Wikidata and to analyze its relationships with Neo4j.

benmarwick

# Adapted from https://stackoverflow.com/a/7267364/1036500 by Andrie de Vries

# This is it: theme(axis.text.x = element_text(angle = 90, hjust = 1, vjust = 0.5))

library(ggplot2)

td <- expand.grid(
  hjust=c(0, 0.5, 1),
  vjust=c(0, 0.5, 1),
  angle=c(0, 45, 90),

walkerke

library(tidycensus)
library(plotly)
library(ggplot2) # devtools::install_github("tidyverse/ggplot2")
library(crosstalk)
# Set your Census API key with `census_api_key()` if not already installed

tx <- get_acs(geography = "county", 
              variables = c(pctcollege = "DP02_0067P", 
                            hhincome = "DP03_0062"), 
              state = "TX", 

JohnMount

#!/bin/bash

# on local
pempath="$1"
ec2target="$2"

ssh -T -i "${pempath}" -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no ubuntu@${ec2target} << 'EOBLOCK'
# on remote machine
sudo apt-get -y update
sudo apt-get -y upgrade

pachadotdev

# Install R
sudo apt-get update
sudo apt-get install gdebi libxml2-dev libssl-dev libcurl4-openssl-dev libopenblas-dev r-base r-base-dev

# Install RStudio
cd ~/Downloads
wget https://download1.rstudio.org/rstudio-xenial-1.1.383-amd64.deb
sudo gdebi rstudio-xenial-1.1.383-amd64.deb
printf '\nexport QT_STYLE_OVERRIDE=gtk\n' | sudo tee -a ~/.profile

palin

import luigi
import luigi.contrib
import luigi.contrib.mysqldb
import MySQLdb

"""
This simple worflow works like this:
1. Read 12 records from reviews table in local revieworld_live DB
2. Insert those 12 records (only review_id and published date) into local luigi_test_1 table in test DB
3. Read 12 records from local luigi_test_1 table in test DB

zhiyzuo

Installing Rattle on MacOS 10.11 (or above)

This article was moved to https://zhiyzuo.github.io/installation-rattle/ !

larsch

#!/bin/sh -exu
dev=$1
cd $(mktemp -d)

function umountboot {
    umount boot || true
    umount root || true
}

# RPi1/Zero (armv6h):