How to use Python left outer join using FOR/LIST/DICTIONARY comprehensions (not SQL)?

2024/9/21 13:50:28

I have two tuples, details below:

t1 = [
['aa'],
['ff'],
['er']
]

t2 = [
['aa', 11,],
['er', 99,]
]

and I would like to get results like these below using python method similar to SQL's LEFT OUTER JOIN:

res = [
['aa', 11,],
['ff',  0,],
['er', 99,]
]

Please help me with this.

Answer
d2 = dict(t2)
res = [[k[0], d2.get(k[0], 0)] for k in t1]
https://en.xdnf.cn/q/72054.html

Related Q&A

GaussianMixture initialization using component parameters - sklearn

I want to use sklearn.mixture.GaussianMixture to store a gaussian mixture model so that I can later use it to generate samples or a value at a sample point using score_samples method. Here is an exampl…

How to use geopy vicenty distance over dataframe columns?

I have a dataframe with location column which contains lat,long location as followsdeviceid location 1102ADb75 [12.9404578177, 77.5548244743]How to get the di…

Opening a postgres connection in psycopg2 causes python to crash

Im getting the following error message when I try to open up a connection to a postgres database. Perhaps its related to OpenSSL, but I cant understand the error message. Can anyone help?>>>…

Calling generated `__init__` in custom `__init__` override on dataclass

Currently I have something like this: @dataclass(frozen=True) class MyClass:a: strb: strc: strd: Dict[str, str]...which is all well and good except dicts are mutable, so I cant use my class to key anot…

Python Watchdog process existing files on startup

I have a simple Watchdog and Queue process to monitor files in a directory. Code taken from https://camcairns.github.io/python/2017/09/06/python_watchdog_jobs_queue.htmlimport time from watchdog.events…

Updating Text In Entry (Tkinter)

The piece of code below takes input from user through a form and then returns the input as multiplied by 2. What I want to do is, when a user types a number (for example 5) and presses the "Enter&…

Python prevent overflow errors while handling large floating point numbers and integers

I am working on a python program to calculate numbers in the Fibonacci sequence. Here is my code:import math def F(n):return ((1+math.sqrt(5))**n-(1-math.sqrt(5))**n)/(2**n*math.sqrt(5)) def fib(n):for…

Python selenium sending keys into textarea

Im using Python 3.4.4 to access a website (https://readability-score.com/) that has a textarea, which dynamically updates when new values are added. Im trying to input a string into that textarea box b…

how to run several executable using python?

I have an executable under linux. I have an 8 core processor. I want to run 8 different instances of the same executable with different arguments.I tried os.system("process_name args")It does…

How to retrieve only arabic texts from a string using regular expression?

I have a string which has both Arabic and English sentences. What I want is to extract Arabic Sentences only.my_string=""" What is the reason ذَلِكَ الْكِتَابُ لَا رَ…