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What is the difference between . (dot) and $ (dollar sign)?
...ppears on the right to the input of whatever appears on the left. This usually also results in fewer parentheses, but works differently.
Going back to the same example:
putStrLn (show (1 + 1))
(1 + 1) doesn't have an input, and therefore cannot be used with the . operator.
show can take an Int...
How to create a zip archive of a directory in Python?
...e. The documentation tells you what functions are available, but doesn't really explain how you can use them to zip an entire directory. I think it's easiest to explain with some example code:
#!/usr/bin/env python
import os
import zipfile
def zipdir(path, ziph):
# ziph is zipfile handle
f...
Importing a CSV file into a sqlite3 database table using Python
...lumn headers in the csv file. And close the connection to the database by calling con.close() at the end.
– Jonas
Aug 8 '16 at 21:31
1
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What's the difference between a proxy server and a reverse proxy server? [closed]
...ccurate, but perhaps too terse.
I will try to add some examples.
First of all, the word "proxy" describes someone or something acting on behalf of someone else.
In the computer realm, we are talking about one server acting on the behalf of another computer.
For the purposes of accessibility, I wi...
How to write very long string that conforms with PEP8 and prevent E501
...
Implicit concatenation might be the cleanest solution:
s = "this is my really, really, really, really, really, really," \
" really long string that I'd like to shorten."
Edit On reflection I agree that Todd's suggestion to use brackets rather than line continuation is better for all the reas...
if/else in a list comprehension
...
You can totally do that. It's just an ordering issue:
[unicode(x.strip()) if x is not None else '' for x in row]
In general,
[f(x) if condition else g(x) for x in sequence]
And, for list comprehensions with if conditions only,
[f...
Is “argv[0] = name-of-executable” an accepted standard or just a common convention?
...
Guesswork (even educated guesswork) is fun but you really need to go to the standards documents to be sure. For example, ISO C11 states (my emphasis):
If the value of argc is greater than zero, the string pointed to by argv[0] represents the program name; argv[0][0] shall b...
List all sequences in a Postgres db 8.1 with SQL
...
The following query gives names of all sequences.
SELECT c.relname FROM pg_class c WHERE c.relkind = 'S';
Typically a sequence is named as ${table}_id_seq. Simple regex pattern matching will give you the table name.
To get last value of a sequence use the ...
How to retrieve a module's path?
...
import a_module
print(a_module.__file__)
Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path = os.path.dirname(a_module.__file__)
To ge...
How do I partially update an object in MongoDB so the new object will overlay / merge with the exist
...n would be that you are happy with $set, but do not want to explicitly set all fields. How would you pass in the data then?
You know you can do the following:
db.collection.update( { _id:...} , { $set: someObjectWithNewData }
...