What is an efficient way that I can trigger some function once the length of a list changes by a certain amount? I have a nested list to which I add data 100 times per second, and I want to trigger a function once the length of the list increased by some value. I tried doing this with an if
Skip every nth index of numpy array
In order to do K-fold validation I would like to use slice a numpy array such that a view of the original array is made but with every nth element removed. For example: If n = 4 then the result would be Note: the numpy requirement is due to this being used for a machine learning assignment where the dependenc…
What does the value of ‘leaf’ in the following xgboost model tree diagram means?
I am guessing that it is conditional probability given that the above (tree branch) condition exists. However, I am not clear on it. If you want to read more about the data used or how do we get this diagram then go to : http://machinelearningmastery.com/visualize-gradient-boosting-decision-trees-xgboost-pyth…
Pandas Timedelta in months
How can I calculate the elapsed months using pandas? I have write the following, but this code is not elegant. Could you tell me a better way? Answer Update for pandas 0.24.0: Since 0.24.0 has changed the api to return MonthEnd object from period subtraction, you could do some manual calculation as follows to…
Python converting sec to min with while and if
When I input 60 or more, it will print just “1”, nothing more. My if is not working. I tried to move “seconds” in front of function but it gave me an error, something like “local variable ‘seconds’ referenced before assignment” Answer I’ll summarize: We th…
How to completely erase the duplicated lines by linux tools?
This question is not equal to How to print only the unique lines in BASH? because that ones suggests to remove all copies of the duplicated lines, while this one is about eliminating their duplicates only, i..e, change 1, 2, 3, 3 into 1, 2, 3 instead of just 1, 2. This question is really hard to write because…
Convert a binary image to 2D array or Matrix in Python?
I’m new to image processing and I’m really having a hard time understanding stuff…so the idea is that how do you create a matrix from a binary image in python? to something like this: It not the same image though the point is there. Thank you for helping, I appreciate it cheers Answer Using …
Database connection string parsing in python
Given a database connection string structure (such like one you can find here) what’s the best way to parse a real URI string and get their component like user, password, database name and host? Thank you very much Answer There is a Python library for that: python 2: urlparse python 3: urllib.parse
Python logging to stdout and log file
I am fairly new in python and starting to get into the logging module. I would like to have the message logged into a log file and outputting to the console. The code below prints out the message to console but how can I get all the message to be log in a file? Logger object does not have a
How can I run a Python script in HTML?
Currently I have some Python files which connect to an SQLite database for user inputs and then perform some calculations which set the output of the program. I’m new to Python web programming and I want to know: What is the best method to use Python on the web? Example: I want to run my Python files wh…