如何提取列表中字典的'g'键值生成新列表并统计小于10的元素数？

Given the list of student dictionaries, here's how to extract the 'g' values and count those less than 10:

1. Extract 'g' values into a new list #

Use a list comprehension to pull the 'g' key's value from each dictionary:

students = [
    {'id': 123, 'name': 'x', 'g': 19},
    {'id': 378, 'name': 'y', 'g': 8},
    {'id': 934, 'name': 'z', 'g': 10}
]

# Generate list of 'g' values
g_scores = [student['g'] for student in students]
print(g_scores)  # Output: [19, 8, 10]

2. Count values less than 10 #

There are two efficient ways to do this:

• Using list comprehension + len():

  count = len([score for score in g_scores if score < 10])
  print(count)  # Output: 2
  

• Using sum() with generator expression (avoids creating an intermediate list, more memory-efficient):

  count = sum(1 for score in g_scores if score < 10)
  print(count)  # Output: 2
  

Combined one-liner (skip storing the intermediate list) #

If you don't need to keep the g_scores list, you can do it in a single step:

count = sum(1 for student in students if student['g'] < 10)
print(count)  # Output: 2

内容的提问来源于stack exchange，提问作者yashar farzizadeh