40 — Report — writing a summary file

One JSON file holds one kind of data; a report combines several. This guide reads a scores file and a players file, computes a short summary — average, top scorer, players per team — and writes one report.txt with file_write from guide 35.

#Steps

1. Create two data files. scores.json pairs each player with a score, and players.json pairs each player with a team:

   [
     {"name": "Mina", "score": 7},
     {"name": "Sana", "score": 9},
     {"name": "Junho", "score": 5}
   ]
   

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   [
     {"name": "Mina", "team": "Seoul"},
     {"name": "Sana", "team": "Busan"},
     {"name": "Junho", "team": "Seoul"}
   ]
   

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   Each file is a list of dicts, exactly like the questions.json from guide 38. The name keys line up, which is how the two files stay about the same players.

2. Load both files with json_load from guide 14. Two calls, two lists:

   use file latest
   scores = json_load("scores.json")
   players = json_load("players.json")
   show f"Loaded {len(scores)} scores and {len(players)} players"
   

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   It prints Loaded 3 scores and 3 players.

3. Walk the scores with a for loop to total them and find the top scorer. The best_score check remembers the biggest value seen so far:

   total = 0
   best_name = ""
   best_score = -1
   for p in scores:
       total = total + p["score"]
       if p["score"] > best_score:
           best_score = p["score"]
           best_name = p["name"]
   average = total / len(scores)
   

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   This is the running-total and running-max pattern from guide 30, now walking dicts instead of plain numbers.

4. Count players per team with a dict. A team seen for the first time starts at 1; a team seen again goes up by one:

   teams = {}
   for p in players:
       team = p["team"]
       if team in teams:
           teams[team] = teams[team] + 1
       else:
           teams[team] = 1
   

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5. Build the report as a list of lines and join them with "\n".join(lines). file_write("report.txt", text) saves the whole text in one call — the same helper that saved each diary note in guide 35:

   lines = []
   lines.append("Match report")
   lines.append("Players: " + str(len(players)))
   lines.append("Average score: " + str(average))
   lines.append("Top scorer: " + best_name + " with " + str(best_score))
   for team in sorted(teams):
       lines.append(team + ": " + str(teams[team]) + " player(s)")
   text = "\n".join(lines)
   file_write("report.txt", text)
   

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   sorted(teams) prints the teams in a stable order, just like the sorted numbers in guide 39.

6. The whole program in one file. Save report.nme:

   # Report: read two JSON data files and write one text summary.
   # Run: nme r report
   # The files scores.json and players.json must exist in the same folder.
   
   use file latest
   
   scores = json_load("scores.json")
   players = json_load("players.json")
   
   show f"Loaded {len(scores)} scores and {len(players)} players"
   
   total = 0
   best_name = ""
   best_score = -1
   for p in scores:
       total = total + p["score"]
       if p["score"] > best_score:
           best_score = p["score"]
           best_name = p["name"]
   
   average = total / len(scores)
   
   teams = {}
   for p in players:
       team = p["team"]
       if team in teams:
           teams[team] = teams[team] + 1
       else:
           teams[team] = 1
   
   lines = []
   lines.append("Match report")
   lines.append("Players: " + str(len(players)))
   lines.append("Average score: " + str(average))
   lines.append("Top scorer: " + best_name + " with " + str(best_score))
   for team in sorted(teams):
       lines.append(team + ": " + str(teams[team]) + " player(s)")
   
   text = "\n".join(lines)
   file_write("report.txt", text)
   
   show "report.txt written:"
   show text
   

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7. Run it, then look at the file it wrote:

   nme r report
   cat report.txt
   

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   Loaded 3 scores and 3 players
   report.txt written:
   Match report
   Players: 3
   Average score: 7.0
   Top scorer: Sana with 9
   Busan: 1 player(s)
   Seoul: 2 player(s)
   

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   Match report
   Players: 3
   Average score: 7.0
   Top scorer: Sana with 9
   Busan: 1 player(s)
   Seoul: 2 player(s)
   

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   The console and the file show the same report: one program turned two data files into one readable summary.

8. Korean uses 파일 사용 최신, json읽기, and 파일쓰기. The full Korean program is in the Korean guide.

#Try it yourself

Add a fourth player to both JSON files and rerun report.nme; the counts and the average update together. Then add a lowest-score line by tracking a worst_score exactly like the best_score check.

#What you learned

• json_load reads each JSON file into its own list of dicts.
• A for loop with a running total and a running max summarizes the scores.
• A dict counts groups such as players per team.
• file_write("report.txt", text) saves a whole multi-line report at once.
• Data files stay data; the program turns them into a report.