[英]Python List not getting appended in fuction
由於變量的值在 function 中沒有改變,我首先運行了一個測試器來測試列表。 事實證明,它們確實附加了 function 中提供的新值。 這是我嘗試過的
def test():
testlist.append(6)
testlist=[3,4]
print(testlist)
test()
print(testlist)
output:-
[3, 4]
[3, 4, 6]
但是當我在我的實際項目中嘗試這個時它沒有用。 這是代碼的一部分:-
student_name=[]
roll_number=[]
def student_info()
sn=input("Student Name : ")
student_name.append(sn)
rn=input("Roll no. : ")
roll_number.append(rn)
student_info() 運行次數與學生數量一樣多,這也是一個變量。
每次,列表都會為每個學生附加一個值。 稍后將在需要時使用索引號提取所有這些值。 但是當我嘗試調用列表值時,它始終是列表的第一個值。 所以列表沒有被附加?
def print_card():
for p in range(0,no_of_classes,1):
for l in range(0,class_strength,1):
print("Student Name:",student_name[l],x*50,"Roll No:",roll_number[l])
(請忽略不必要的復雜格式化部分)
#This is the main part of the code.
for j in range (no_of_classes):
class_=input("Class name")
print("Class strength of ",class_)
class_strength=int(input())
for i in range (class_strength):
student_info()
print_card()
這是最小的可重現程序
student_name=[]
roll_number=[]
def student_info():
sn=input("Student Name : ")
student_name.append(sn)
rn=input("Roll no. : ")
roll_number.append(rn)
def print_card():
for p in range(0,no_of_classes,1):
for l in range(0,class_strength,1):
x=' '
print('\n')
print("Student Name:",student_name[l],x*50,"Roll No:",roll_number[l])
no_of_classes=2
class_strength=1
for j in range (0,no_of_classes):
for i in range (0,class_strength):
student_info()
print_card()
該卡是為第一個 class 創建的,但對於下一個 class,相同的 output 來了。 為什么會這樣?
預期 output 與實際 output
(比如說2個學生)
kode skool
Student Name: 1 Roll No: 1
Class: 1 Section: 1
Address 1
1
City: 1 Pin Code: 1
Guardian's Phone Number 1
kode skool
Student Name: 2 Roll No: 2
Class: 2 Section: 2
Address 2
2
City: 2 Pin Code: 2
Guardian's Phone Number 2
-------------------------------------------------------------------
kode skool
Student Name: 1 Roll No: 1
Class: 1 Section: 1
Address 1
1
City: 1 Pin Code: 1
Guardian's Phone Number 1
kode skool
Student Name: 1 Roll No: 1
Class: 1 Section: 1
Address 1
1
City: 1 Pin Code: 1
Guardian's Phone Number 1
你所有的問題是你把所有學生都放在一個單一的名單上
students = [name1, name2, name3, ...]
所以后來你很難獲得第二個 class 的正確數據。
您使用索引[0]
、 [1]
等從第二個 class 獲取學生,但它需要
[class_1_strength + 0], [class_1_strength + 1], etc.
要從第三個 class 獲得學生,您需要
[class_1_strength + class_2_strength + 0], [class_1_strength + class_2_strength + 1], etc.
所以這是個大問題。
如果您將每個 class 保留為子列表,那就簡單多了
school = [
[name1, name2, name3, ...], # class 1
[name1, name2, name3, ...], # class 2
# etc.
]
或作為字典:
school = {
'class_1_name': [name1, name2, name3, ...], # class 1
'class_2_name': [name1, name2, name3, ...], # class 2
# etc.
}
坦率地說,將所有值保持在一起會很好:
school = [
[ (name1, roll_number, ...), (name2, roll_number, ...), ...], # class 1
[ (name1, roll_number, ...), (name2, roll_number, ...), ...], # class 2
# etc.
]
最小的工作示例。
我使用random
, string
只為測試創建一些數據 - 所以我不必使用input()
。
我使用random.seed(0)
來獲取始終相同的數據 - 所以我可以將它們與之前的執行進行比較。
import random
import string
random.seed(0)
def generate_random_name(lenght=5):
return "".join(random.choices(string.ascii_uppercase, k=lenght))
def get_student_info():
#student_name = input("Student Name : ")
#roll_number = input("Roll no. : ")
student_name = generate_random_name()
roll_number = 1
return student_name, roll_number
def print_card():
for class_number, class_students in enumerate(school, 1):
print('--- class:', class_number, '---\n')
for item in class_students:
student_name, roll_number, class_number = item
print(f"Student Name: {student_name:}")
print(f"Roll No: {roll_number}")
print(f"Class: {class_number}")
print()
# --- main ---
school = []
no_of_classes = 2
class_strength = 3
for class_number in range(1, no_of_classes+1):
class_students = [] # list for all students in one clas
for student_number in range(1, class_strength+1):
student_name, roll_number = get_student_info()
# all information about one student
item = [student_name, student_number, class_number]
class_students.append(item)
school.append(class_students)
print_card()
結果:
--- class: 1 ---
Student Name: VTKGN
Roll No: 1
Class: 1
Student Name: KUHMP
Roll No: 2
Class: 1
Student Name: XNHTQ
Roll No: 3
Class: 1
--- class: 2 ---
Student Name: GXZVX
Roll No: 1
Class: 2
Student Name: ISXRM
Roll No: 2
Class: 2
Student Name: CLPXZ
Roll No: 3
Class: 2
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