多行列数字/单词出现统计：科目成绩达标人数与频次分析求助

Hey there! Let's tackle this problem step by step. Based on your file structure (each line follows student_name subject1 grade1 subject2 grade2 ...), here's a practical Python solution that covers all your requirements: counting students with grades >5 per subject, tallying grade frequencies, and finding the most common grade for each subject.

Step 1: Solution Code #

from collections import defaultdict, Counter

# Initialize a data structure to track each subject's metrics
subject_stats = defaultdict(lambda: {
    "students_above_5": set(),  # Use a set to avoid duplicate student counts
    "grade_frequencies": Counter()
})

# Read and process the file (replace "grades.txt" with your actual file path)
with open("grades.txt", "r") as file:
    for line in file:
        line_parts = line.strip().split()
        if not line_parts:
            continue  # Skip empty lines
        
        student_name = line_parts[0]
        # Iterate over subject-grade pairs (start at index 1, step by 2)
        for idx in range(1, len(line_parts), 2):
            subject = line_parts[idx]
            grade = int(line_parts[idx + 1])  # Convert grade to integer
            
            # Update students with grades >5
            if grade > 5:
                subject_stats[subject]["students_above_5"].add(student_name)
            # Update grade frequency count
            subject_stats[subject]["grade_frequencies"][grade] += 1

# Print the final statistics for each subject
for subject, stats in subject_stats.items():
    print(f"=== {subject} Statistics ===")
    # Count of students with grade >5
    print(f"Students with grade >5: {len(stats['students_above_5'])}")
    # Grade occurrence counts
    print("Grade frequency breakdown:")
    for grade, count in sorted(stats["grade_frequencies"].items()):
        print(f"  Grade {grade}: {count} occurrences")
    # Most common grade(s) (handle ties)
    most_common_grades = stats["grade_frequencies"].most_common()
    if most_common_grades:
        max_count = most_common_grades[0][1]
        top_grades = [str(g) for g, c in most_common_grades if c == max_count]
        print(f"Most common grade(s): {', '.join(top_grades)} (appeared {max_count} times)")
    print()

Step 2: Key Explanations #

• Data Structure Choice: We use defaultdict to automatically initialize metrics for new subjects, and Counter to effortlessly tally grade frequencies. A set is used for students with grades >5 to ensure each student is counted only once per subject (even if there were duplicate entries in the file).
• File Parsing: Each line is split into parts, then we loop through pairs of elements (subject followed by grade) starting from index 1.
• Handling Ties: The most_common() method returns grades sorted by frequency. We check for ties by collecting all grades that match the highest frequency count.

Example Output #

Using your sample input line:

Robert Java 8 Algorithms 8 Math 6 Andrew Java 9 Algorithms 7 Math 5

The code would output:

=== Java Statistics ===
Students with grade >5: 2
Grade frequency breakdown:
  Grade 8: 1 occurrences
  Grade 9: 1 occurrences
Most common grade(s): 8, 9 (appeared 1 times)

=== Algorithms Statistics ===
Students with grade >5: 2
Grade frequency breakdown:
  Grade 7: 1 occurrences
  Grade 8: 1 occurrences
Most common grade(s): 7, 8 (appeared 1 times)

=== Math Statistics ===
Students with grade >5: 1
Grade frequency breakdown:
  Grade 5: 1 occurrences
  Grade 6: 1 occurrences
Most common grade(s): 5, 6 (appeared 1 times)

Quick Adjustments #

• If your grades are decimals instead of integers, replace int(line_parts[idx + 1]) with float(line_parts[idx + 1]).
• To save results to a file instead of printing, replace the print() calls with file write operations.

内容的提问来源于stack exchange，提问作者Szabolcs-Ervin Szigeti