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Wrote this function in python that transposes a matrix:
def transpose(m):
height = len(m)
width = len(m[0])
return [ [ m[i][j] for i in range(0, height) ] for j in range(0, width) ]
In the process I realized I don"t fully understand how single line nested for loops execute. Please help me understand by answering the following questions:
- What is the order in which this for loop executes?
- If I had a triple nested for loop, what order would it execute?
- What would be equal the equal unnested for loop?
Given,
[ function(i,j) for i,j in object ]
- What type must object be in order to use this for loop structure?
- What is the order in which i and j are assigned to elements in object?
- Can it be simulated by a different for loop structure?
- Can this for loop be nested with a similar or different structure for loop? And how would it look?
Additional information is appreciated as well.
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InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately
3 answers
Tried to perform REST GET through python requests with the following code and I got error.
Code snip:
import requests
header = {"Authorization": "Bearer..."}
url = az_base_url + az_subscription_id + "/resourcegroups/Default-Networking/resources?" + az_api_version
r = requests.get(url, headers=header)
Error:
/usr/local/lib/python2.7/dist-packages/requests/packages/urllib3/util/ssl_.py:79:
InsecurePlatformWarning: A true SSLContext object is not available.
This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail.
For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
InsecurePlatformWarning
My python version is 2.7.3. I tried to install urllib3 and requests[security] as some other thread suggests, I still got the same error.
Wonder if anyone can provide some tips?
Answer #1
The docs give a fair indicator of what"s required., however requests
allow us to skip a few steps:
You only need to install the security
package extras (thanks @admdrew for pointing it out)
$ pip install requests[security]
or, install them directly:
$ pip install pyopenssl ndg-httpsclient pyasn1
Requests will then automatically inject pyopenssl
into urllib3
If you"re on ubuntu, you may run into trouble installing pyopenssl
, you"ll need these dependencies:
$ apt-get install libffi-dev libssl-dev
Dynamic instantiation from string name of a class in dynamically imported module?
3 answers
In python, I have to instantiate certain class, knowing its name in a string, but this class "lives" in a dynamically imported module. An example follows:
loader-class script:
import sys
class loader:
def __init__(self, module_name, class_name): # both args are strings
try:
__import__(module_name)
modul = sys.modules[module_name]
instance = modul.class_name() # obviously this doesn"t works, here is my main problem!
except ImportError:
# manage import error
some-dynamically-loaded-module script:
class myName:
# etc...
I use this arrangement to make any dynamically-loaded-module to be used by the loader-class following certain predefined behaviours in the dyn-loaded-modules...
Answer #1
You can use getattr
getattr(module, class_name)
to access the class. More complete code:
module = __import__(module_name)
class_ = getattr(module, class_name)
instance = class_()
As mentioned below, we may use importlib
import importlib
module = importlib.import_module(module_name)
class_ = getattr(module, class_name)
instance = class_()
How to get all of the immediate subdirectories in Python
3 answers
I"m trying to write a simple Python script that will copy a index.tpl to index.html in all of the subdirectories (with a few exceptions).
I"m getting bogged down by trying to get the list of subdirectories.
Answer #1
import os
def get_immediate_subdirectories(a_dir):
return [name for name in os.listdir(a_dir)
if os.path.isdir(os.path.join(a_dir, name))]
We hope this article has helped you to resolve the problem. Apart from Single Line Nested For Loops, check other code Python module-related topics.
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Singapore | 2023-01-27
Maybe there are another answers? What Single Line Nested For Loops exactly means?. Checked yesterday, it works!
Prague | 2023-01-27
Maybe there are another answers? What Single Line Nested For Loops exactly means?. Will get back tomorrow with feedback
Warsaw | 2023-01-27
Thanks for explaining! I was stuck with Single Line Nested For Loops for some hours, finally got it done 🤗. Will use it in my bachelor thesis