tungwaiyip.info

home

about me

links

Media

Yucatán Photos

St Lucia Photos

Photo Album

Videos

Blog

< May 2010 >
SuMoTuWeThFrSa
       1
2 3 4 5 6 7 8
9101112131415
16171819202122
23242526272829
3031     

past articles »

Click for San Francisco, California Forecast

San Francisco, USA

 

Python CSV reader is much faster than pickle

If you are considering to serialize a large amount of data to the disk, performance may become a concern to you. Python provides a serialization tool in the pickle module. There is also an optimized version called the cPickle. But how do they perform?

The data of concern to me is tabular data. In order to do a bake off, I have generated 50,000 records of sample data. The CSV representation is shown below:

seq, name, address, city, age, birthday
1000,John M. Doe,2147 Main St.,Middle Town 14,47,1985-05-15
1001,John N. Doe,2148 Main St.,Middle Town 15,48,1985-05-16
1002,John O. Doe,2149 Main St.,Middle Town 16,49,1985-05-17
1003,John P. Doe,2150 Main St.,Middle Town 17,50,1985-05-18
1004,John Q. Doe,2151 Main St.,Middle Town 18,51,1985-05-19
1005,John R. Doe,2152 Main St.,Middle Town 19,52,1985-05-20
1006,John S. Doe,2153 Main St.,Middle Town 20,53,1985-05-21
1007,John T. Doe,211 Main St.,Middle Town 21,1,1985-05-22
...

Naturally, CSV is a contender for storing tabular data. (Indeed the data source I'm working with is in CSV format.) The two pickle modules produce identical data output. In addition, Python 2.6 also provides a JSON module that do the similar task as pickle but outputs a standard text based format. I included it in the comparison below.

First observation, CSV output the most compact data at 3MB. Pickle output is 40% larger at 4.2MB. JSON is somewhere in between. The speed? CSV is the winner among them all.


Method Load Time (ms) File size (MB)
CSV 188 3
CSV int 289 3
cPickle 692 4.2
pickle 1,815 4.2
JSON 4,975 3.9

Note that CSV reader create data items as string. In the sample data, two out of the six columns are integer fields. In order to do an apple-to-apple comparison I have another test that do integer conversion after loading such that the data loaded is identical to pickle's. This impacted the performance somewhat. But it is still more than twice as fast as the faster cPickle module. The standard library's JSON's performance trailing far behind, making it unsuitable for anything performance intensive. FYI, unlike the other modules, JSON's output is in unicode.

The test is done by Python 2.6 on Windows XP machine with 2.33GHz Core2 CPU (Download source code).


2010.05.12 [, ] - comments

 

 

blog comments powered by Disqus

past articles »

 

BBC News

 

Trump-Russia ties: Senate pledges thorough inquiry (30 Mar 2017)

 

Insurer Lloyd's of London confirms new Brussels subsidiary (30 Mar 2017)

 

Ivanka Trump to be assistant to US president (30 Mar 2017)

 

'Exploding' soup dumpling video angers Asian foodies (30 Mar 2017)

 

Brexit: UK to set out plans to replace all EU laws (30 Mar 2017)

 

Turkey: Euphrates Shield campaign in Syria 'ended' (30 Mar 2017)

 

PwC keeps Oscars despite best film blunder (30 Mar 2017)

 

North Carolina 'bathroom' law: Deal reached on repeal (30 Mar 2017)

 

Trump to meet China's Xi in Florida next week (30 Mar 2017)

 

Italian police in Venice arrest three Jihadists (30 Mar 2017)

more »

 

SF Gate

 

Bay Area News (7 Jan 2012)

 

City Insider (11 Feb 2012)

 

Crime Scene (13 Feb 2012)

 

C.W Newius Column (10 Jan 2012)

 

C.W. Nevius Blog (11 Feb 2012)

 

Education News (10 Jan 2012)

 

KALW (11 Feb 2012)

 

Matier and Ross Blog (11 Feb 2012)

 

Bill to let bars serve alcohol until 4 a.m. advances (29 Mar 2017)

 

Pinterest seeks new ad revenue sources ahead of possible IPO (29 Mar 2017)

 

Westinghouse files for bankruptcy (29 Mar 2017)

 

Man sentenced in iPhone frauds (29 Mar 2017)

 

PG&E agrees to .5m penalty in San Bruno fallout; bills to drop (29 Mar 2017)

 

Top General Says Human Rights Shouldn't Hold Up U.S. Arms Sales (29 Mar 2017)

more »

 


Site feed Updated: 2017-Mar-30 03:00