do this with list comp?
noemail at noemail4u.com
Thu Dec 18 19:44:42 CET 2003
On Fri, 12 Dec 2003 10:46:58 -0600, John Hunter
<jdhunter at ace.bsd.uchicago.edu> wrote:
>I want to replace all empty fields in a CSV line with 'NULL'.
>Here is a brute force way
> def fixline(line):
> ret = 
> for s in line.split(','):
> if not len(s): ret.append('NULL')
> else: ret.append(s)
> return ret
> line = 'John,Bill,,,Fred'
> print fixline(line)
> # ['John', 'Bill', 'NULL', 'NULL', 'Fred']
>I am wondering if there is a way to do it with list comprehensions. I
>know how I would do it with a ternary operator.....
I'd go with Dave Brueck's answer:
[x or 'NULL' for x in line.split(',')]
The "trick" here is the "hidden" ternary operator.
By saying "x or 'NULL' ", you are expressing the equivalent of what
would look in C, et al, like:
x ? x : 'NULL'
In other words, if x is not null/None/empty/nil/false, evaluate to x.
Otherwise, evaluate to 'NULL'.
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