MEDOC (MEdline DOwnloading Contrivance)

More information about MEDOC on OMICTools website or on MEDOC's publication on arXiv.org:

• https://arxiv.org/abs/1710.06590

• https://omictools.com/medline-downloading-contrivance-tool

About

What is MEDLINE ?

MEDLINE is a database of scientitifc articles released by the NIH. Pubmed is the most common way to query this database, used daily by many scientists around the world.

The NIH provides free APIs to build automatic queries, however a relational database could be more efficient.

The aim of this project is to download XML files provided by MEDLINE on a FTP and to build a relational mySQL database with their content.

Launch

Clone this repository

The first step is to clone this Github repository to your local machine.

Open a terminal.

git clone "https://github.com/MrMimic/MEDOC"
cd ./MEDOC

Setup

Here prerequisites and installation procedures will be discussed.

Prerequisites

XML parsing libraries may be needed. You can install them on any Debian-derived system with:

> sudo apt-get install libxml2-dev libxslt1-dev zlib1g-dev

You may also need python-dev. You can also install it with the same command: > sudo apt-get install python-dev

Installation

The second step is to install external dependencies and to cythonize python functions.

Thus, run the file SETUP.py

cd /path/to/MEDOC
python3 utils/SETUP.py build_ext --inplace

This script will:

• Check for pip3 and give command to install it
• Check for Cython and give command to install it
• Check for pymysql and give command to install it
• Check for bs4 and give command to install it

There's no need to Cythonize functions anymore, they've been optimized.

Alternatively you can exploit the requirements.txt file shipped with the project. Simply run the following command from the MEDOC folder.

> pip3 install -r requirements.txt

bs4==0.0.1
beautifulsoup4==4.6.0
Cython==0.27.2
html5lib==0.999999999
lxml==3.5.0
PyMySQL==0.7.11

Configuration

Before you can run the code, you should take a look at parameters.json file and customize it according to your environment.

Plus, if you have already a user to access the DB you wish to create you can change the schema file to reflect that. You can change the DB_USER and the DB_PASSWORD fields with the following command. Suppose your credentials are: my_custom_user/my_secret_password

export MEDOC_SQL_FILE='database_creation.sql'
sed -i'' -e "s/\bdb_user\b/my_custom_user/g" $MEDOC_SQL_FILE
sed -i'' -e "s/\bDB_PASSWORD\b/my_secret_password/g" $MEDOC_SQL_FILE

NOTE: If python3 is your default, you do not need to specify python3 or pip3 but just use python and pip.

Launch the programm

Open file 'parameters.json' and change complete path value including your /home/xxx/...

If your computer has 16Go or more of RAM, you can set 'insert_command_limit' to '1000' of greater.

Leave database name to 'pubmed' but change the mySQL password to yours.

Then, simply execute :

python3 __execution__.py 

Output

First line should be about database creation and number of files to download.

Then, a regular output for a file loading should look like:

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DOWNLOADING FILE
Downloading baseline/medline17n0216.xml.gz ..
Elapsed time: 12.32 sec for module: download
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - FILE EXTRACTION
Elapsed time: 0.42 sec for module: extract
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - XML FILE PARSING
Elapsed time: 72.47 sec for module: parse
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - SQL INSERTION
10000 articles inserted for file baseline/medline17n0216.xml.gz
20000 articles inserted for file baseline/medline17n0216.xml.gz
30000 articles inserted for file baseline/medline17n0216.xml.gz
Total time for file medline17n0216.xml.gz: 5.29 min

Issues

Program stop running because of 'Segmentation fault (core dumped)'

Indexing a file with 30K article take some time and RAM. Try to open the function /lib_medline/python_functions/E_parse_xml.py and go to the line:

soup = BeautifulSoup(file_content, 'lxml')

Change 'lxml' to 'html-parser' and re-launch SETUP.py.

Or simply try to lower the 'insert_command_limit' parameter, to insert values more often in the database, thus saving RAM usage.

SQL insertions are taking really a lot of time (more than 15min / file)'

Recreate the SQL database after dropping it, by running the following command:

DROP DATABASE pubmed ;

Then, comment every line about indexes (CREATE INDEX) or foreigns keys (ALTER TABLE) into the SQL creation file. Indexes are slowing up insertions.

When the database is full, launch the indexes and alter commands once at a time.

Problem installing lxml Make sure you have all the right dependencies installed On Debian based machines try running:

sudo apt-get install python-dev libxml2-dev libxslt1-dev zlib1g-dev