RegularExpression-Python

Posted on 2023-04-14 Edited on 2025-06-30 In python

今天有想在這裡分享 Regular Expression，這也是大家不想碰到的，可就是一個很復雜的就越耗用。
我也沒有很勵害，但之前開發自動化，用很多。因此想藉由這編文章來寫下我所寫道的筆記和參考很多教學。

在介紹之前我們在 python 都會用到 re 或是 rex ，但在這我只會分享用 re，也就是要 import re，不然不能用。

常用的 req module

Module	說明
match	Determine if the RE matches at the beginning of the string.
search	Scan through a string, looking for any location where this RE matches
findall	Find all substrings where the RE matches, and returns them as a list.
finditer	Find all substrings where the RE matches, and returns them as an iterator.

compile()

import re
text ='https://chenchih.page , Author is ChenChih'
pattern=re.compile('Chenchih',re.I)
print(pattern.match(text)) #None
print(pattern.search(text).group()) #chenchih
print(pattern.findall(text)) #['chenchih', 'ChenChih']

output:

None
cheenchih > > ['chenchih', 'ChenChih']

match()

This function matches a regular expression pattern at the beginning of a string. If the pattern is found, it returns a match object, otherwise, it returns None.

import re
teststring="123abc456789abc123ABC"
pattern=re.compile(r"abc")
match=pattern.match(teststring)
print(match)

MY-SQL(Basic)

Posted on 2022-11-29 Edited on 2025-06-30

我想分享一些基本的DB(MYSQL)語法。之前面試有考不管是在Amazon，或Microsoft 都有考過我DB。我那時有準備筆記，但後來就不知跑哪。今天想在這篇寫關於SQL基本指令，有機會再寫高階的語法。

我住前是用MYSQL的DB軟體，你們可以選用其他的如MogoDB, Microsoft SQL server，orlacle DB等等。基本上語法都差不多，我猜的

Table: employee:

+----+-------+--------+--------------+
| id | Name  | Salary | DepartmentID |
+----+-------+--------+--------------+
|  1 | Joe   | 85000  | 1            |
|  2 | Henry | 80000  | 2            |
|  3 | Sam   | 60000  | 1            |
|  4 | Max   | 90000  | 1            |
|  5 | Janet | 69000  | 1            |
|  6 | Randy | 85000  | 1            |
+----+-------+--------+--------------+

SELECT & FROM

select * from

select 可以選擇要印那一欄，如果加*可以把所有內如印出來，以下是指令:

select * from employee;

Table: employee;
+----+-------+--------+--------------+
| id | Name  | Salary | DepartmentID |
+----+-------+--------+--------------+
|  1 | Joe   | 85000  | 1            |
|  2 | Henry | 80000  | 2            |
|  3 | Sam   | 60000  | 1            |
|  4 | Max   | 90000  | 1            |
|  5 | Janet | 69000  | 1            |
|  6 | Randy | 85000  | 1            |
+----+-------+--------+--------------+

select Name 指定欄位

SELECT Name, Salary From Employee;

Set

Posted on 2022-11-24 Edited on 2025-06-30 In python

An unorder collection of a unquie object. No duplicate value.
不可以有重複的直，一般都是用在帳號上面。

Create set

1 2	my_set= {1,2,3,4,5} print(my_set)

output:

{1, 2, 3, 4, 5}

如果加重複會用最前面的

1 2	my_set= {1,2,3,4,5,5} print(my_set)

output:

{1, 2, 3, 4, 5}

adding set

my_set= {1,2,3,4,5,5}
my_set.add(100)
my_set.add(2)
print(my_set)

output

‘{1, 2, 3, 4, 5, 100}`

Dictionary

Posted on 2022-11-24 Edited on 2025-06-30 In python

今天想分享如何用 dictionary 字典方式存資料。

key and Value 如何使用宣槓取直

collection of of {key:value} pairs

no duplicate

allow changeable and ordered

declare dictionary 宣告 dict

It's an unorder , it's not next to each other, so we can't use index like we use in list. Dictionary will have a a key and value look like this:

syntax:

declare: dictname= {key:value}
get key: print(dictname['key'])

Access and Get value 取我們的直:

dict={
    'keyA':1,
    'keyB':2
}

取 key 的直: print(dict['keyA']) => 1
取所有直 print(dict) => {'keyA': 1, 'keyB': 2}

宣告不同 data type

Tuple

Posted on 2022-11-24 Edited on 2025-06-30 In python

Tuple is like list, but we can;t modify it, they are immutable. Tuple immutable 直，就是他的直不無法修改的，有些語法是用const類似這概念。

Create Tuple 建立tuple

# Empty tuple
my_tuple = ()
print(my_tuple) #()

# Tuple having integers
my_tuple = (1, 2, 3) 
print(my_tuple) #(1,2,3)

# tuple with mixed datatypes
my_tuple = (1, "Hello", 3.4) 
print(my_tuple) #(1, "Hello", 3.4) 

# multiply value
x,y,z, *other = (1,2,3,4,5)
print(f"x: {x}, y:{y}, z:{z}, other:{other}")
#x: 1, y:2, z:3, other:[4, 5]

my_tuple = ("mouse", [8, 4, 6], (1, 2, 3))
print(my_tuple) #('mouse', [8, 4, 6], (1, 2, 3))

created without using parentheses

my_tuple = 3, 4.6, "dog"
print(my_tuple)

# tuple unpacking is also possible
a, b, c = my_tuple

print(a)      # 3
print(b)      # 4.6
print(c)      # dog

my_tuple = ("hello")
print(type(my_tuple))  # <class 'str'>

# Creating a tuple having one element
my_tuple = ("hello",)
print(type(my_tuple))  # <class 'tuple'>

# Parentheses is optional
my_tuple = "hello",
print(type(my_tuple))  # <class 'tuple'>

Access Tuple Elements

# Accessing tuple elements using indexing
my_tuple = ('p','e','r','m','i','t')

print(my_tuple[0])   # 'p' 
print(my_tuple[5])   # 't'

# nested tuple
n_tuple = ("mouse", [8, 4, 6], (1, 2, 3))

# nested index
print(n_tuple[0][3])  #'s'
print(n_tuple[1][1])  # 4

# Negative indexing for accessing tuple elements

my_tuple = ('p', 'e', 'r', 'm', 'i', 't')

# Output: 't'
print(my_tuple[-1])
# elements beginning to 2nd
# Output: ('p', 'r')
print(my_tuple[:-7])

Slicing

Function or Method

Posted on 2022-11-23 Edited on 2025-06-30 In python

python 有很多不同 function，因此我想在這篇寫所有 funtion 我會用到。我指的 function 不是傳 function，而是一些 libary function

Math

Datetime 時間

time

程式跑的時間

如果計算程式袍多就可以用這方法

import time

# starting time
start = time.time()
# your code
for i in range(1,60):
    print(i)

#endtime
end = time.time()
runtime=end - start
print(" Runtime of the program is {runtime:%.8f}")
print(f"Runtime of the program is {runtime:.5f}")
#or
print(f"Runtime of the program is {(end - start):.5f}")

datetime

今天日期

date.today 取今天日期

pandas

Posted on 2022-11-23 Edited on 2025-06-30 In python

Pandas 筆記

今天我想分享我學的 pandas 筆記，我覺得對於分大數據很有幫助，他有點像 mysql。請先下載 module 或 package:pip install pandas`

Part1 基本語法

連線 CSV 檔案

可以去 github 找相關 csv 檔案，然後去 raw 檔案做連線

import pandas as pd
url = "https://raw.githubusercontent.com/mwaskom/seaborn-data/master/tips.csv"
tips = pd.read_csv(url)

print(tips)

pandas 會回傳 DataFrame 格式。<class 'pandas.core.frame.DataFrame'>
下面是印出所有資料表內容。

     total_bill   tip     sex smoker   day    time  size
0         16.99  1.01  Female     No   Sun  Dinner     2
1         10.34  1.66    Male     No   Sun  Dinner     3
2         21.01  3.50    Male     No   Sun  Dinner     3
3         23.68  3.31    Male     No   Sun  Dinner     2
4         24.59  3.61  Female     No   Sun  Dinner     4
..          ...   ...     ...    ...   ...     ...   ...
239       29.03  5.92    Male     No   Sat  Dinner     3
240       27.18  2.00  Female    Yes   Sat  Dinner     2
241       22.67  2.00    Male    Yes   Sat  Dinner     2
242       17.82  1.75    Male     No   Sat  Dinner     2
243       18.78  3.00  Female     No  Thur  Dinner     2

Head and Tail

head(N): 是查前面 N 筆資料

Excel_ReadWrite

Posted on 2022-10-23 Edited on 2025-06-30 In python

Create empty Excel File

import openpyxl
fn = 'new_excel.xlsx'
wb = openpyxl.Workbook()
wb.save(fn)

Create Sheet工作表的

Create Empty Sheet 新增工作

import openpyxl
fn = 'new_excel.xlsx'
wb = openpyxl.Workbook()
wb.create_sheet("Sheet1", 0) 
wb.create_sheet("Sheet2", 1)
wb.save(fn)

Read Excel Sheet 讀取excel檔案每個工作表的名稱

import openpyxl
fn = 'new_excel.xlsx'
wb = openpyxl.load_workbook(fn)
print(wb.sheetnames)
print(wb.active)
print(wb.active.title)

output:

1
2
3

['Sheet1', 'Sheet2', 'Sheet']
<Worksheet "Sheet1">
Sheet1

edit Name of worksheet 修改工作表名稱

List and ZIP

Posted on 2022-10-23 Edited on 2025-06-30 In python

list 列印

這裡會包含以下內內容:

基本讀 list 搭配 for
*list (快速讀 list 不需要用到 for loop)
N 筆後換
轉換 list 到字串(搭配 join)
enumerate 方法
Method:
- split
- slice
- copy
- zip
- 轉換 list 理的 tuple 到 list

常用的方式印 list 內容

list : list = ['A','B','C','D','E','F']

我們可以用以下方法:

- `for` loop

list= [1,2,3]
for i in list:
    print(i, end=" ") #
print()

output:

1 2 3

- `*`list: 不需要 for loop ，可以 unpack list

substringSearchg檔案內容搜尋相關關鍵字

Posted on 2022-10-18 Edited on 2025-06-30 In python

今天分享如何搜尋字串裡面的 substring 或如果有檔案(log)想找相關字來做分析。

split() 方式

我的 string 是:

st="[20221013.162853.788442][info]:[[40;32m>>> DL- ingress traffic: 0.010799(Mbps), egress traffic: 0.087016(Mbps), ReTx: 0.000220(Mbps)[0m]"

我想抓出時間和TPUT的直，如:
[20221013.162853.788442] 和 0.010799(Mbps) 同時要把 [] 和 (Mbps)移除，可以用下面方式:

Step1: 宣告我的 string

1	st="[20221013.162853.788442][info]:[[40;32m>>> DL- ingress traffic: 0.010799(Mbps), egress traffic: 0.087016(Mbps), ReTx: 0.000220(Mbps)[0m]"

Step2 抓取時間直

1 2	dateStr = st.split('[', 1)[1].split(']')[0] print(dateStr) #20221013.162853.788442

output:

20221013.162853.788442

常用的 req module

compile()

match()

SELECT & FROM

select * from

select Name 指定欄位

Create set

adding set

key and Value 如何使用宣槓取直

declare dictionary 宣告 dict

Access and Get value 取我們的直:

宣告不同 data type

Create Tuple 建立tuple

created without using parentheses

Access Tuple Elements

# Negative indexing for accessing tuple elements

Slicing

Math

Datetime 時間

time

程式跑的時間

datetime

今天日期

Pandas 筆記

Part1 基本語法

連線 CSV 檔案

Head and Tail

Create empty Excel File

Create Sheet工作表的

Create Empty Sheet 新增工作

Read Excel Sheet 讀取excel檔案每個工作表的名稱

edit Name of worksheet 修改工作表名稱

list 列印

常用的方式印 list 內容

- for loop

- *list: 不需要 for loop ，可以 unpack list

split() 方式

- `for` loop

- `*`list: 不需要 for loop ，可以 unpack list