• ## Send you a good way to sort Python data

Time：2022-5-6

Summary:Learning the pandas sorting method is a good way to start or practice basic data analysis using python. The most common data analysis is done using spreadsheets, SQL, or pandas. One of the advantages of using pandas is that it can process a large amount of data and provide high-performance data operation capability. This article […]

• ## Get the maximum and minimum records in each group Mongo vs MySQL

Time：2022-5-5

Count the maximum and minimum records in each group Mongo implementation { “_id” : “01001”, “city” : “AGAWAM”, “pop” : 15338, “state” : “MA” } For complete JSON, see:http://media.mongodb.org/zips… demand Get the city with the largest population and the city with the smallest population in each state and the corresponding population db.zipcodes.aggregate( {\$group: {_id:{state:”\$state”,city:”\$city”}, popPerCity:{\$sum:”\$pop”} […]

• ## Force deduction leetcode algorithm foundation 21 day question brushing record ①

Time：2022-4-30

Force buckle [leetcode]Basic algorithm 21 days brush questionsRecord one Vegetable chicken algorithm swipe questions and punch in!! ⭐ Binary search 34. Find the first and last position of an element in a sorted array Given an integer array nums arranged in ascending order and a target value target. Find the start and end positions of […]

• ## 09 / 05 leetcode hot topic Hot 100 — 22, 23, 31

Time：2022-4-25

22. bracket generation class Solution { 23. Merge K ascending linked lists Solution 1: merge two linked lists at a time /** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ class Solution { public ListNode mergeKLists(ListNode[] […]

• ## C# advanced chapter – getting to know LINQ

Time：2022-4-15

preface Reminder: in order to learn the knowledge points more thoroughly and remember them more firmly, I will write down the knowledge through teaching explanation, because in the process, people will change from students to teachers. This process will excavate new knowledge and views. It is a process of deep excavation and improvement of knowledge […]

• ## JS sorts the array in order according to multiple object attributes

Time：2022-4-11

1、 Situation encountered You need to sort the array by attribute 1, attribute 2, attribute 3… In ascending or descending order of priority   2、 Solution Using the sort sorting method of data in JS, Const arr = [data content to be sorted] arr.sort (this. Comparetype (‘attribute name ‘,’ attribute name 1 ‘,’ attribute name […]

• ## He problem record – Combinatorial Mathematics

Time：2022-4-5

Binary number 2 ^ k Canon hard(worth doing!) analysis For condition “as”2kHexadecimal number, except the last digit,rEach bit of is strictly smaller than the one adjacent to its right“NamelyNumbers from left to right are in ascending order That is, find the combination number(since the scheme corresponding to the combination number is disordered, we can regard […]

• ## Pandas data analysis exercise 9

Time：2022-4-5

Exercise 9 – time series Explore Apple stock price data Step 1 import the necessary Libraries Run the following code import pandas as pd import numpy as np # visualization import matplotlib.pyplot as plt %matplotlib inline Step 2 dataset address Run the following code #Import dataset from destination path path9 = ‘D:/hailong/hailong_download/pandas_exercise/exercise_data/Apple_stock.csv’ Step 3: the […]

• ## IOS algorithm (basic) — delete duplicate elements in the sorting linked list

Time：2022-3-22

There is a linked list arranged in ascending order. Give you the head node of the linked list. Please delete all duplicate elements so that each element appears only once. Returns a linked list of results in the same ascending order.1. The number of nodes in the linked list is within the range [0, 300] […]

• ## The most detailed openpyxl tutorial of Excel module (IV) – filtering and sorting operations

Time：2022-2-20

In the previous tweets, we introduced the use of openpyxl to set up formulas, and other related tweets can be obtained from the relevant menu at the bottom of this official account. In the next tweet, let’s learn other knowledge in the python module openpyxl. This tweet will see how to use Python to sort. […]

• ## Init . Initialization order of RC

Time：2022-2-12

Previously sorted out the initialization sequence of Android 7, which is outdated. Reorganize and release it based on Android 11 to facilitate viewing the problems and bugs related to the initialization sequence in RC <!– more –> [Android 11] Code can be seenhttp://aosp.opersys.com/xref/… Initialization language visible /system/core/init/README.md perhaps https://blog.csdn.net/u010753159/article/details/51981121 I won’t talk about this here, […]

• ## MySQL query summary

Time：2022-1-22

mysql Part I: data preparation 1 create student table create table student ( student_number varchar(20) primary key, student_name varchar(20) not null, student_sex varchar(20) not null default “men”, check(student_sex=’men’ OR student_sex=’women’), check(student_number>99 AND student_number<200), student_birthday datetime, class varchar(20) ); Extension (check constraint) student_ Number is greater than 99 and less than 200 student_ The sex value […]