File I/O Python - Tutorial

1

Buka & Tutup File

Cara membuka file secara manual dengan open() dan close().

Python
# Buka file untuk baca
file = open("data.txt", "r")  # "r" = read mode
# ... proses file di sini ...
# wajib tutup!
file.close()

💡 Mode File:
"r" = read (baca) | "w" = write (tulis, overwrite) | "a" = append (tambah)
"rb" = read binary | "wb" = write binary

📝 Contoh lengkap:

Python
# Buka file teks
f = open("test.txt", "w")
f.write("Halo dunia!")
f.close()
# Baca lagi
f = open("test.txt", "r")
content = f.read()
f.close()
print(content)  # Halo dunia!

2

Baca File (Read)

Plusieurs cara membaca isi file.

1. read() - Baca Semua

Python
f = open("data.txt", "r")
isi = f.read()
f.close()
print(isi)

2. readline() - Baca Baris Pertama

Python
f = open("data.txt", "r")
baris1 = f.readline()
baris2 = f.readline()
f.close()
print(baris1)  # baris pertama
print(baris2)  # baris kedua

3. readlines() - Baca Semua jadi List

Python
f = open("data.txt", "r")
semua = f.readlines()
f.close()
# semua jadi list
for i, baris in enumerate(semua):
print(f"{i}: {baris}")

4. For Loop - Cara Pythonic

Python
with open("data.txt", "r") as f:
for baris in f:
print(baris.strip())  # strip() hapus enter

3

Tulis File (Write)

Cara menulis/menyimpan data ke file.

1. write() - Tulis Satu Kalimat

Python
f = open("output.txt", "w")  # w = write (hapus semua dulu)
f.write("Baris pertama")
f.close()

2. writelines() - Tulis List

Python
data = ["apel\n", "pisang\n", "jeruk\n"]
f = open("buah.txt", "w")
f.writelines(data)
f.close()

3. append() - Tambah Tanpa Hapus

Python
# a = append (tambah di akhir, tidak overwrite)
f = open("log.txt", "a")
f.write("Log baru ditambahkan\n")
f.close()

⚠️ Peringatan: Mode "w" akan menghapus semua isi file! Gunakan "a" untuk menambah.

4. Contoh Lengkap: Simpan Data Dinamis

Python
siswa = [
{"nama": "Budi", "nilai": 85},
{"nama": "Ani", "nilai": 90},
]
# Simpan ke file
with open("siswa.txt", "w") as f:
for s in siswa:
f.write(f"{s['nama']},{s['nilai']}\n")

4

JSON File

JSON (JavaScript Object Notation) - format_data populer untuk simpan data structured.

Install JSON (sudah Built-in)

Tidak perlu install, cukup import:

Python

1import json

1. dump() - Simpan JSON ke File

Python
data = {
"nama": "Dani",
"usia": 25,
"hobi": ["coding", "musik"]
}
# Simpan ke file JSON
with open("data.json", "w") as f:
json.dump(data, f, indent=2)

2. load() - Baca JSON dari File

Python
# Baca dari file JSON
with open("data.json", "r") as f:
data = json.load(f)
print(data["nama"])  # Dani
print(data["hobi"])  # ['coding', 'musik']

3. dumps() - JSON ke String

Python
data = {"status": "ok"}
# convert ke string JSON
json_str = json.dumps(data)
print(json_str)  # {"status": "ok"}

4. loads() - String ke Dict

Python
json_str = '{"status": "ok"}'
# convert string ke dict
data = json.loads(json_str)
print(data["status"])  # ok

5

CSV File

CSV (Comma Separated Values) - format spreadsheet.

Install csv

csv juga sudah built-in:

Python

1import csv

1. writerow() - Tulis Baris CSV

Python
with open("siswa.csv", "w", newline="") as f:
writer = csv.writer(f)
# Header
writer.writerow(["Nama", "Nilai", "Kelas"])
# Data
writer.writerow(["Budi", "85", "XII-A"])
writer.writerow(["Ani", "90", "XII-A"])

2. reader() - Baca CSV

Python
with open("siswa.csv", "r") as f:
reader = csv.reader(f)
# Skip header
header = next(reader)
# Baca semua data
for row in reader:
print(row)  # ['Budi', '85', 'XII-A']

3. DictWriter - Simpan dengan Nama Kolom

Python
with open("anggota.csv", "w", newline="") as f:
fieldnames = ["nama", "email"]
writer = csv.DictWriter(f, fieldnames=fieldnames)
writer.writeheader()
writer.writerow({"nama": "Budi", "email": "budi@email.com"})
writer.writerow({"nama": "Ani", "email": "ani@email.com"})

6

Context Manager (with)

Context manager with adalah cara aman & pythonic untuk buka file.

✅ Keuntungan with:
- Auto close file даже jika ada error
- Kode lebih bersih
- Tidak perlu手动 close()

Syntax with

Python
with open("file.txt", "r") as file:
# proses file
isi = file.read()
# file sudah ditutup otomatis di sini

Contoh with untuk JSON

Python
import json
# Baca JSON
with open("config.json") as f:
config = json.load(f)
# Tulis JSON
with open("config.json", "w") as f:
json.dump(config, f, indent=2)

Multiple Files

Python
# Buka banyak file sekaligus
with open("input.txt") as a, \
     open("output.txt", "w") as b:
b.write(a.read().upper())

7

Path & OS Module

Kelola path file dan direktori dengan OS module.

OS Module - Operasi File

Python
import os
# Cek apakah file ada
print(os.path.exists("data.txt"))  # True/False
# Hapus file
os.remove("data.txt")
# Rename file
os.rename("lama.txt", "baru.txt")

OS Module - Direktori

Python
import os
# Buat folder
os.mkdir("folder_baru")
# Daftar isi folder
files = os.listdir(".")
print(files)
# Ambil path sekarang
print(os.getcwd())  # current working directory

Pathlib - Cara Modern

Python
from pathlib import Path
# Buat path object
p = Path("data/file.txt")
# Cek ada
print(p.exists())
# Nama file
print(p.name)    # file.txt
print(p.stem)    # file
print(p.suffix)   # .txt
print(p.parent) # data/

📁 File I/O Python

1. read() - Baca Semua

2. readline() - Baca Baris Pertama

3. readlines() - Baca Semua jadi List

4. For Loop - Cara Pythonic

1. write() - Tulis Satu Kalimat

2. writelines() - Tulis List

3. append() - Tambah Tanpa Hapus

4. Contoh Lengkap: Simpan Data Dinamis

Install JSON (sudah Built-in)

1. dump() - Simpan JSON ke File

2. load() - Baca JSON dari File

3. dumps() - JSON ke String

4. loads() - String ke Dict

Install csv

1. writerow() - Tulis Baris CSV

2. reader() - Baca CSV

3. DictWriter - Simpan dengan Nama Kolom

Syntax with

Contoh with untuk JSON

Multiple Files

OS Module - Operasi File

OS Module - Direktori

Pathlib - Cara Modern