1. Lặp các phần tử trong list đồng thời lấy index
Junior
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| x = ['a', 'b', 'c']
counter = 0
for e in x:
print('%d: %s' % (counter, e))
counter += 1
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Senior
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| x = ['a', 'b', 'c']
for i, e in enumerate(x):
print('%d: %s' % (i, e))
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Output:
2. Lặp các phần tử trong tử điển đồng thời lấy key và value
Junior
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| d = {'a': 10, 'b': 20, 'c': 30}
for k in d.keys():
print('%s: %d' % (k, d[k]))
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Senior 1
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| d = {'a': 10, 'b': 20, 'c': 30}
for k, v in d.items():
print('%s: %d' % (k, v))
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Senior 2
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| d = {'a': 10, 'b': 20, 'c': 30}
for i, (k, v) in enumerate(d.items()):
print('%d. %s: %d' % (i, k, v))
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Output:
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| 1. c: 30
2. b: 20
3. a: 10
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3. Lặp từng cặp phần tử trong 2 danh sách (dùng zip)
Junior
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| m = [0, 1, 2]
n = ['a', 'b', 'c']
counter = 0
for i in range(len(m)):
print('%d. %d <-> %s' % (i, m[i], n[i]))
counter += 1
print('\n')
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Senior
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| m = [0, 1, 2]
n = ['a', 'b', 'c']
for i, (mx, nx) in enumerate(zip(m, n)):
print('%d. %d <-> %s' % (i, mx, nx))
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Output:
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| 0. 0 <-> a
1. 1 <-> b
2. 2 <-> c
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4. Thay đổi mỗi phần tử trong danh sách (dùng list comprehensive)
Junior
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| p = [1, 2, 3]
for k in range(len(p)):
p[k] *= 2
print(p)
print('\n')
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Senior (list comprehensive)
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| p = [1, 2, 3]
p = [e*2 for e in p]
print(p)
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Output:
5. Lọc phần tử trong danh sách (dùng list comprehensive)
Junior
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| list_input = [1, 2, 3, 4]
list_output = []
for element in list_input:
if element % 2 == 0:
list_output.append(element)
print(list_output)
print('\n')
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Senior (list comprehensive)
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| list_input = [1, 2, 3, 4]
list_output = [e for e in list_input if e % 2 == 0]
print(list_output)
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Output:
6. “Ternary” trong Python
Junior
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| x = 10
if x > 5:
x = 5
else:
pass # do nothing
print(x)
print('\n')
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Senior (ternary)
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| x = 10
x = 5 if x > 5 else x
print(x)
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Output:
7. Gọi hàm với tham số dạng danh sách (list) hoặc từ điển (dict)
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| def foo(key, value):
print('key: %s | value: %s' % (str(key), str(value)))
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Junior
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| foo(1, 'a')
foo(2, 'b')
foo(3, 'c')
foo(4, 'd')
foo(5, 'e')
foo(6, 'f')
foo(7, 'g')
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Senior 1
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| params = [(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd'), (5, 'e'), (6, 'f'), (7, 'g')]
for p in params:
foo(*p) # params passing by list / tuple: *p
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Senior 2
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| params = [
{'key': 1, 'value': 'a'},
{'key': 2, 'value': 'b'},
{'key': 3, 'value': 'c'},
{'key': 4, 'value': 'd'},
{'key': 5, 'value': 'e'},
{'key': 6, 'value': 'f'},
{'key': 7, 'value': 'g'}
]
for p in params:
foo(**p) # params passing by dictionary: **p
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Output:
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| key: 1 | value: a
key: 2 | value: b
key: 3 | value: c
key: 4 | value: d
key: 5 | value: e
key: 6 | value: f
key: 7 | value: g
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8. Gọi hàm động trong Python
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| def foo(key, value):
print('foo key: %s | foo value: %s' % (str(key), str(value)))
def bar(key, value):
print('bar key: %s | bar value: %s' % (str(key), str(value)))
func = 'bar' # 'foo' or 'bar'
params = [(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd'), (5, 'e'), (6, 'f'), (7, 'g')]
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Junior: does not know how to call “func” function multiple times with the given params. :((.
Senior: just uses “eval” to get function pointer and call it with the given params. :)).
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| func_pointer = eval(func)
for p in params:
func_pointer(*p)
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Output:
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| bar key: 1 | bar value: a
bar key: 2 | bar value: b
bar key: 3 | bar value: c
bar key: 4 | bar value: d
bar key: 5 | bar value: e
bar key: 6 | bar value: f
bar key: 7 | bar value: g
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9. Kiểm tra động thuộc tính trong đối tượng (dùng hasattr, getattr, setattr)
Senior says:
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| class Senior():
def __init__(self):
pass
def set_dynamic_field(self, field, value):
setattr(self, field, value)
def get_dynamic_field(self, field):
if not hasattr(self, field):
return None
return getattr(self, field)
s = Senior()
s.set_dynamic_field('name', 'HELLO')
print(s.name)
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Junior: what the f*ck?? I’m done.
Output:
10. Dùng hàm dựng sẵn trong Python (min, max, sum, sorted, …)
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| x = [4, 3, 6, 8, 10, 72]
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Junior: it’s easy. Let me calculate sum, min, max by using “for” loop :D.
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| sum_val = 0
for v in x:
sum_val += v
min_val = x[0]
for v in x:
min_val = v if v < min_val else min_val # junior: haha, I'm using "ternary" :D.
max_val = x[0]
for v in x:
max_val = v if v > max_val else max_val
print('sum: %d' % sum_val)
print('min: %d' % min_val)
print('max: %d' % max_val)
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Senior: what are you doing? See it.
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| print('sum: %d' % sum(x))
print('min: %d' % min(x))
print('max: %d' % max(x))
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Junior: …
Output:
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| sum: 103
min: 3
max: 72
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