Internal material.
Today's content:
-(1) Get used to list, append ()
-(2) Functions int (), float ()
-(3) Functions range (), list (range ())
-(4) for statement
-(5) Review questions
--ʻAppend (A)` adds element A to the end of the list.
#review
#What is output?
a = [7, 8, 'taro', 'jack']
print(a)
print(a[2])
#What is output?
a = [7, 8, 'taro', 'jack']
a.append('10')
print(a)
a.append(10)
print(a)
#10 and'10'Is another.
# [7, 8, 'taro', 'jack', '10', 10]
--Tips for specifying the position of the list: [-1] = The minus 1st position is the end.
#What is output?
a = [7, 8, 'taro', 'jack']
print(a)
print(a[3])
print(a[-1])
#When the number of elements is 4, the address"[3]"And address"[-1]"Is the same.
--You can also put a list in the list.
#What is output?
a = [7, 8, 'taro', 'jack']
b = ['ML', 3.14]
a.append(b)
print(b)
print(a[-1])
print(a[-1][0])
print(a[-1][1])
--ʻInt (A) : Convert A to an integer. --
float (A)`: Convert A to a real number.
#What is output?
b = '5'
c = int(b)
print(b)
print(c)
d = 5.5
e = int(d)
print(d)
print(e)
f = 1.234
g = float(f)
print(f)
print(g)
(3) range(), list(range())
--ʻInt (A) : Convert A to an integer. --
float (A): Convert A to a real number. --
list (A)`: Convert A to list type.
A = range(10)
print(A)
B = list(range(10))
print(B)
C = list(range(1,11))
print(C)
D = list(range(1,11,2))
print(D)
E = list(range(11,1,-2))
print(E)
# [2000,2004,2008,2012,2016,2020]How can I display?
# [2020,2016,2012,2008,2004,2000]How can I display?
The output result of print (range (5))
is different between Python2 and Python3.
# python3
$ print(range(5))
range(0,5)
# python2
$ print(range(5))
[0,1,2,3,4]
--If the content to be repeated can be summarized in one line
for [rules for repetition]:
\ _ Tab \ _ [Repeat]
――If the content to be repeated spans two lines
for [rules for repetition]:
\ _ Tab \ _ [Repeat]
\ _ Tab \ _ [Repeat]
Make blocks using tabs like this. This is a Python rule designed to make it easier to read (more readable). Failure to do this in a for loop will result in errors and unintended consequences.
For example
list_a = ['Tokyo', 'Cambridge', 'Ann Arbor', 'Pittsburgh']
When displaying the list in order, the following two are often used.
--Turn "serial number ʻi" to 0-3 to display "ʻi
th element in the list"
for i in range(4):
\ _ Tab \ _ print (list_a [i])
--"Take out the elements of the list one by one and display them"
for a in list_a:
\ _ Tab \ _ print (a)
list_name = ['Taro', 'Jack', 'Tom', 'Andy', 'Jason']
print(list_name)
for x in list_name:
print(x)
print('---')
for i in range(10):
print(i)
print('---')
for i in range(2000,2021,4):
print(i)
print('---')
for i in range(2020,1999,-4):
print(i)
print('---')
N_people = len(list_name)
for i in range(N_people):
print(i, list_name[i])
for i in range(0,N_people,2):
print(i, list_name[i])
print('--. . . --')
# Q.What do you think you will see?
list_name = ['Taro', 'Jack', 'Tom', 'Andy', 'Jason', 'Matt']
list_name.append('John')
list_name.append('Madoka')
list_name.append('Ichiro')
print(list_name)
N_people = len(list_name)
print(N_people)
for i in range(1,N_people,3):
print(i, list_name[i])
ʻIf (condition A): \ _ Tab \ _
Read if" condition A is met "`
ʻIf (condition A): \ _ Tab \ _
Read if" condition A is met " ʻElse:
# Other
\ _ Tab \ _ Read if" condition A is not met "
ʻIf (condition A): \ _ Tab \ _
" Satisfy condition A " ʻElif (Condition B):
\ _ Tab \ _ " Condition A is not met "and" Condition B is met "
ʻElse: # Other \ _ Tab \ _
" Condition A is not met "and" Condition B is not met "`
x = 5
if (x>0):
print('x=', x, '(This is larger than 0.)')
x = -3
if (x>0):
print('x=', x, '(This is larger than 0.)')
else :
print('x=', x, '(This is NOT larger than 0.)')
x = -3
if (x>0):
print('x=', x, '(x>0)')
elif (x>-10) :
print('x=', x, '(-10 < x < 0)')
else :
print('x=', x, '(otherwise)')