tungwaiyip.info

home

about me

links

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

 

North Korea's Kim Jong-un crosses into South Korea (27 Apr 2018)

 

Golden State Killer suspect traced using genealogy websites (27 Apr 2018)

 

EX-CIA chief Mike Pompeo confirmed as secretary of state (26 Apr 2018)

 

How police line-ups jail the innocent (26 Apr 2018)

 

Special master appointed in Trump lawyer Michael Cohen's case (27 Apr 2018)

 

EU member states to vote on near-total neonicotinoids ban (27 Apr 2018)

 

Alberto Fujimori: Peru ex-president faces forced sterilisation charges (26 Apr 2018)

 

Australia's Crown casino fined for 'blanking' slot machines (27 Apr 2018)

 

Spain 'wolf pack' case: Thousands protest over rape ruling (26 Apr 2018)

 

Bill Cosby found guilty of sexual assault in retrial (26 Apr 2018)

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)

 

British lawmakers call on Zuckerberg to appear before them (26 Apr 2018)

 

Fed officials worry the economy is too good. Workers still feel left behind (26 Apr 2018)

 

Ship traffic, April 27 (26 Apr 2018)

 

YouTube overhauls kids’ app after complaints about content (26 Apr 2018)

 

Twitter falls after warning growth will slow this year (25 Apr 2018)

 

Business News Roundup, April 26 (25 Apr 2018)

more »

 


Site feed Updated: 2018-Apr-26 21:00