第一階段複習

siriuskoan

Outline

變數與型別
邏輯判斷 if
迴圈 for、while
string
list
dict
函式
module

先複習一下 IO

 name = input("輸入名字: ")
print("Your name is", name, sep=" ", end="!")

變數與型別

變數是存放值的容器
型別代表這個變數(值)的類型

型別

int
str
float
list
…

運算子

+、-、*、/、//
&、|、^、~
and、or、not

範例

 # int
a = 1
a2 = a + 5
a3 = a2 * 2
# float
b = 1.0
# str
c = str(a)
c *= 10
# list
d = [1, "1"]

Quiz

階段考不會出現

What's the output?

 a = 12
a = str(a)
 
a1 = int(a) + 1
a2 = a * 2
a3 = int(a) + 3 // 2
 
print(a1, a2, a3)
print(type(a1), type(a2), type(a3))

邏輯判斷 `if`

判斷一個條件是否為真，並根據結果做不同的事情

範例

 score = int(input("輸入分數: "))
if score >= 90:
    print("A+")
elif score >= 85:
    print("A")
elif score >= 80:
    print("A-")
else:
    print("no A")

`=` vs. `==`

=
- 賦值
- 把一個變數的值設定成某個值
==
- 判斷
- 判斷兩個值是不是相同

Quiz

What's the output?

 # credit to 鄧人豪
x = 2
y = 3
bool1 = x == y
bool2 = x = y
print(bool1, bool2)
print(x, y)

迴圈 `for`、`while`

在某個條件成立時重複執行特定片段的程式

while
- 通常在有一個確定條件來決定是否要迴圈時使用
- 如: name == ""
for
- 通常在確定(常數或是變數都可以)要跑幾次的時候使用
- 如: 倒數計時器

範例

 # while
name = input("請輸入名字: ")
while name == "":
    print("名字不得為空")
    name = input("請輸入名字: ")
print("Welcome, " + name)

範例

 # for
import time
 
count = int(input("從多少開始倒數: "))
for i in range(count, -1, -1):
    print("倒數到: " + str(count))
    time.sleep(1)
print("倒數結束")

迴圈控制

break
- 直接中斷現在的整個迴圈
continue
- 跳過現在正在進行的這一次迴圈

範例

 name = input("請輸入名字: ")
while True:
    print("名字不得為空")
    name = input("請輸入名字: ")
    if name != "":
        break
print("Welcome, " + name)

範例

range 左閉右開

 MAX = 0
for n in range(10):
    n = int(input("輸入 0 ~ 100 的數字: "))
    if n > 100 or n < 0:
        print("範圍錯誤")
        continue
    MAX = max(MAX, n)
print("最大值是 " + str(MAX))

巢狀迴圈

 for i in range(1, 10):
    for j in range(1, 10):
        print(f"{i}*{j}={i*j}", end=" ")
    print()

Quiz

輸出 0 到 1 的每個小數，取到小數點後第二位
即，\(0.00,0.01,0.02,...,0.99,1.00\)

Ans

 for i in range(0, 101):
    print("%.2f" % round(i / 100, 2))

String

一大堆字連在一起

範例

 s1 = "abc"
s2 = 'abc'
s3 = """abc
123"""

字串格式化

 name = "siriuskoan"
print("My name is {}".format(name))
print(f"My name is {name}")

字串操作

 string = "I love cat"
# 長度
print(len(string))
# 索引
print(string[2])
# 分割
print(string[2:6])

字串處理函式

 string = "I love dog"
# replace
print(string.replace("dog", "cat"))
# find
dog_index = string.find("dog")
print(f"The word dog is at {dog_index} to {dog_index + 2}")
# split
data = "Shohei Ohtani,57,17,.298".split(",")
print(f"Player: {data[0]} AB: {data[1]} \
H: {data[2]}, AVG: {data[3]}")

字串處理函式 (cont.)

 # join
like = ["Reading", "Coding", "Gaming"]
print("I like " + ", ".join(like))
# strip
name = input("名字: ")
# name is "     siriuskoan             "
print(name.strip())

`list`

可以裝好幾項資料的資料結構

範例

 li = [1, 2, 3]
for ele in li:
    print(ele)
# or
for i in range(len(li)):
    print(li[i])

分割

 li = [1, 2, 3, 4, 5, 6, 7, 8, 9]
print(li[0:5])
print(li[:-1])
print(li[::-1])

串列操作

 li = [1, 2, 3, 4, 5]
li.append(6)
li.extend([7, 8])
li.insert(0, 0)
print(li.index(3))
print(li.count(1))
li.pop()
li.remove(0)
li.clear()

串列操作 (cont.)

 li = [2, 3, 9, 7, 6, 0]
 
print(list(reversed(li)))
li.reverse()
 
print(sorted(li))
li.sort()

`list` 的指派

 L1 = [1, 2, 3, 4, 5]
L2 = L1
L2[0] = -1
print(L1, L2) # 相同

vs.

 L1 = [1, 2, 3, 4, 5]
L2 = L1.copy() # or L1[:]
L2[0] = -1
print(L1, L2) # 只有 L2 被改掉

`enumerate`

 li = [1, 2, 3, 4, 5]
for index, value in enumerate(li):
    print(f"Index {index} is {value}")

`map`、`filter`

 li = [-2, 2, 3, -10, 8, -7, 1]
li = list(map(abs, li))

 li = [-2, 2, 3, -10, 8, -7, 1]
def check_larger_than_zero(n):
    return True if n > 0 else False
li = list(filter(check_larger_than_zero, li))

`dict`

字典
對鍵值對 (key-value pair) 做一對一的對應
key 必須要 immutable (不可變動)

範例

 d = {"name": "siriuskoan", "age": 19, "gender": "male"}
print(d["name"])
# solve key error
print(d.get("name"))
# 更改值
d["name"] = "phkoan"
# 新增 key
d["department"] = "CS"
# 刪除 key
del d["gender"]

`dict` 遍歷

 d = {"name": "siriuskoan", "age": 19, "gender": "male"}
for value in d.values():
    print(value)
for key in d.keys():
    print(key)
for k, v in d.items():
    print(f"key {k} with value {v}")

JSON

 import json
json_data = """
{"name": "siriuskoan", "hobby": ["reading", "coding"]}
"""
d = json.loads(json_data)

Function

把一塊程式碼包起來，以利後續使用及功能區分

範例

 def say_hello(name):
    print(f"Hello, {name}")
    
def add(a, b, c = 0):
    return a + b + c

Asterisks

 def add(*numbers):
    s = 0
    for n in numbers:
        s +=  n
    return s
 
def mapping(**kv):
    for k, v in kv.items():
        print(f"{k}: {v}")

Scope

會先從自己的 symbol table 找，找不到再去 global

 g = 10
def f():
    print(g)
    g = 5
f()

 g = 10
def f():
    global g
    print(g)
    g = 5
f()

建議變數用傳的，不要扯到一堆 global、local 的問題

`lambda`

匿名函式

 INPUT = "2139023, 3242, 34.2, 23, 43".split(", ")
print(list(map(lambda x: int(x) ** 3 + 1, INPUT)))

遞迴

自己呼叫自己
注意終止條件及邊界處理

 def fib(n):
    if n == 0 or n == 1:
        return 1
    return fib(n - 1) + fib(n - 2)
 
print(fib(10))

Module

一整份 (可能是一個或多個 python 檔案) 可以讓你引用的程式

`import`

引入 python 檔案或函式庫

 import math
print(math.sqrt(4))
 
import math as MATH
print(MATH.sqrt(4))
 
from math import sqrt
print(sqrt(4))
 
from math import sqrt as s
print(s(4))

`import`

強烈建議不要用 from module import * 這種寫法

virtual environment

讓開發者可以針對不同專案獨立出不同開發環境的好幫手

使用

安裝 virtualenv 套件

$ pip install virtualenv

建立新的虛擬環境

$ virtualenv venv

進入虛擬環境

$ .\venv\Scripts\activate

這時候應該會看到 prompt 前面多出 (venv)

使用

進到去之後，就是一個完全與外部無關的環境了
接著可以開始安裝需要的套件等等

1

第一階段複習 siriuskoan

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changed 2 years ago 247 views

	name = input("輸入名字: ")
	print("Your name is", name, sep=" ", end="!")

	# int
	a = 1
	a2 = a + 5
	a3 = a2 * 2
	# float
	b = 1.0
	# str
	c = str(a)
	c *= 10
	# list
	d = [1, "1"]

	a = 12
	a = str(a)

	a1 = int(a) + 1
	a2 = a * 2
	a3 = int(a) + 3 // 2

	print(a1, a2, a3)
	print(type(a1), type(a2), type(a3))

	score = int(input("輸入分數: "))
	if score >= 90:
	print("A+")
	elif score >= 85:
	print("A")
	elif score >= 80:
	print("A-")
	else:
	print("no A")

	# credit to 鄧人豪
	x = 2
	y = 3
	bool1 = x == y
	bool2 = x = y
	print(bool1, bool2)
	print(x, y)

	# while
	name = input("請輸入名字: ")
	while name == "":
	print("名字不得為空")
	name = input("請輸入名字: ")
	print("Welcome, " + name)

	# for
	import time

	count = int(input("從多少開始倒數: "))
	for i in range(count, -1, -1):
	print("倒數到: " + str(count))
	time.sleep(1)
	print("倒數結束")

	name = input("請輸入名字: ")
	while True:
	print("名字不得為空")
	name = input("請輸入名字: ")
	if name != "":
	break
	print("Welcome, " + name)

	MAX = 0
	for n in range(10):
	n = int(input("輸入 0 ~ 100 的數字: "))
	if n > 100 or n < 0:
	print("範圍錯誤")
	continue
	MAX = max(MAX, n)
	print("最大值是 " + str(MAX))

	for i in range(1, 10):
	for j in range(1, 10):
	print(f"{i}{j}={ij}", end=" ")
	print()

	name = "siriuskoan"
	print("My name is {}".format(name))
	print(f"My name is {name}")

	string = "I love cat"
	# 長度
	print(len(string))
	# 索引
	print(string[2])
	# 分割
	print(string[2:6])

	string = "I love dog"
	# replace
	print(string.replace("dog", "cat"))
	# find
	dog_index = string.find("dog")
	print(f"The word dog is at {dog_index} to {dog_index + 2}")
	# split
	data = "Shohei Ohtani,57,17,.298".split(",")
	print(f"Player: {data[0]} AB: {data[1]} \
	H: {data[2]}, AVG: {data[3]}")

	# join
	like = ["Reading", "Coding", "Gaming"]
	print("I like " + ", ".join(like))
	# strip
	name = input("名字: ")
	# name is " siriuskoan "
	print(name.strip())

	li = [1, 2, 3]
	for ele in li:
	print(ele)
	# or
	for i in range(len(li)):
	print(li[i])

	li = [1, 2, 3, 4, 5, 6, 7, 8, 9]
	print(li[0:5])
	print(li[:-1])
	print(li[::-1])

	li = [1, 2, 3, 4, 5]
	li.append(6)
	li.extend([7, 8])
	li.insert(0, 0)
	print(li.index(3))
	print(li.count(1))
	li.pop()
	li.remove(0)
	li.clear()

	li = [2, 3, 9, 7, 6, 0]

	print(list(reversed(li)))
	li.reverse()

	print(sorted(li))
	li.sort()

	L1 = [1, 2, 3, 4, 5]
	L2 = L1.copy() # or L1[:]
	L2[0] = -1
	print(L1, L2) # 只有 L2 被改掉

	li = [1, 2, 3, 4, 5]
	for index, value in enumerate(li):
	print(f"Index {index} is {value}")

	li = [-2, 2, 3, -10, 8, -7, 1]
	def check_larger_than_zero(n):
	return True if n > 0 else False
	li = list(filter(check_larger_than_zero, li))

	d = {"name": "siriuskoan", "age": 19, "gender": "male"}
	print(d["name"])
	# solve key error
	print(d.get("name"))
	# 更改值
	d["name"] = "phkoan"
	# 新增 key
	d["department"] = "CS"
	# 刪除 key
	del d["gender"]

	d = {"name": "siriuskoan", "age": 19, "gender": "male"}
	for value in d.values():
	print(value)
	for key in d.keys():
	print(key)
	for k, v in d.items():
	print(f"key {k} with value {v}")

	import json
	json_data = """
	{"name": "siriuskoan", "hobby": ["reading", "coding"]}
	"""
	d = json.loads(json_data)

	def say_hello(name):
	print(f"Hello, {name}")

	def add(a, b, c = 0):
	return a + b + c

	def add(*numbers):
	s = 0
	for n in numbers:
	s += n
	return s

	def mapping(**kv):
	for k, v in kv.items():
	print(f"{k}: {v}")

	INPUT = "2139023, 3242, 34.2, 23, 43".split(", ")
	print(list(map(lambda x: int(x) ** 3 + 1, INPUT)))

	def fib(n):
	if n == 0 or n == 1:
	return 1
	return fib(n - 1) + fib(n - 2)

	print(fib(10))

	import math
	print(math.sqrt(4))

	import math as MATH
	print(MATH.sqrt(4))

	from math import sqrt
	print(sqrt(4))

	from math import sqrt as s
	print(s(4))