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Using Python to write to an Excel / OpenOffice Calc spreadsheet on Ubuntu Linux

Date: 2010-02-15  |   Tags: linux, python, ubuntu   |   2 Comments

Via Matt Harrison's blog post, here is how to write Excel or OpenOffice.org Calc spreadsheet files using Python and the xlwt library. Xlwt is a fork of pyExcelerator which handles only writing spreadsheet files. For reading spreadsheets, see xlrd. Note, these libraries don't use COM, so they will work on non-Windows OSes, such as Linux. For more information, see Matt's blog post. He even has a PDF cheat sheet.

  • Install pip
  • Install xlwt 
    sudo pip install -U xlwt
  • Create an example script: 
    import xlwt

DATA = (("The Essential Calvin and Hobbes", 1988,),
        ("The Authoritative Calvin and Hobbes ...
... read more »

Python setdefault example

Date: 2010-02-09  |   Tags: data_structures, python   |   3 Comments

I always forget how to use Python's setdefault dictionary operation so here is a quick example.

What I want:

DATA_SOURCE = (('key1', 'value1'),
               ('key1', 'value2'),
               ('key2', 'value3'),
               ('key2', 'value4'),
               ('key2', 'value5'),)

newdata = {}
for k, v in DATA_SOURCE:
    if newdata.has_key(k):
        newdata[k].append(v)
    else:
        newdata[k] = [v]
print newdata

Results:

{'key2': ['value3', 'value4', 'value5'], 'key1': ['value1', 'value2']}

Better way using setdefault:

newdata = {}
for k, v in DATA_SOURCE:
    newdata.setdefault(k, []).append(v)
print newdata

The results are the same.

... read more »

A hack to copy files between two remote hosts using Python

Date: 2010-02-08  |   Modified: 2010-02-16  |   Tags: files_directories, linux, python, ssh, ubuntu   |   1 Comment

I sometimes need to copy a file (such as a database dump) between two remote hosts on EC2. Normally this involves a few steps: scp'ing the ssh keyfile to Host 1, ssh'ing to Host 1, looking up the address for Host 2, then scp'ing the desired file from Host 1 to Host 2.

I was excited to read in the man page that scp can copy files between two remote hosts directly. However, it didn't work for me. Apparently, running scp host1:myfile host2: is like running ssh host1 scp myfile host2: so I still need ...

... read more »

Iterating over lines in multiple Linux log files using Python

Date: 2010-01-23  |   Modified: 2010-02-24  |   Tags: files_directories, linux, python, ubuntu   |   3 Comments

I needed to parse through my Nginx log files to debug a problem. However, the logs are separated into many files, most of them are gzipped, and I wanted the ordering within the files reversed. So I abstracted the logic to handle this into a function. Now I can pass a glob pattern such as /var/log/nginx/cache.log* to my function, and iterate over each line in all the files as if they were one file. Here is my function. Let me know if there is a better way to do this.

Update 2010-02-24:To handle multiple log ...

... read more »

"ImportError: No module named pstats" error on Ubuntu

Date: 2010-01-21  |   Tags: error, python, ubuntu   |   2 Comments

Even though the pstats module (used by cProfile) is part of the Python Standard Library, Ubuntu requires installing a separate package because of its non-free license. For more information, see this Ubuntu bug report. (thanks Luke)

Running this on Ubuntu Karmic:

import cProfile
def my_super_slow_routine(): pass
cProfile.run('my_super_slow_routine()')

Produces this error:

Traceback (most recent call last):
  File "test_pstats_error.py", line 3, in 
    cProfile.run('my_super_slow_routine()')
  File "/usr/lib/python2.6/cProfile.py", line 36, in run
    result = prof.print_stats(sort)
  File "/usr/lib/python2.6/cProfile.py", line 80, in print_stats
    import pstats
ImportError: No module named pstats

Solution ...

... read more »
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