Reading Data with Python | Easy Learning

01-read.py

# Read entire file one time
page = ""
with open("app.log", 'r') as file:
    page = file.read()
print(page)
"""
# Output
03/22 08:51:06 TRACE  :...read_physical_netif: Home list entries returned = 7
03/22 08:51:06 INFO   :...read_physical_netif: index #0, interface VLINK1 has address 129.1.1.1, ifidx 0
...
"""
print("*" * 80)
# Read lines 
lines = []
with open("app.log", 'r') as file:
    lines = file.readlines()
print(lines[0])
"""
# Output
03/22 08:51:06 TRACE  :...read_physical_netif: Home list entries returned = 7
"""

02-read.py

# Read line by line
rows = []
with open("app.log", 'r') as file:
    index = 0
    for line in file:
        date, time, type, *rest = line.split()
        rows.append(
            {
                "index": index,
                "date": date,
                "time": time,
                "type": type,
                "line": " ".join(rest),
            }
        )
        index += 1
print(rows[2])
"""
# Output
{'index': 2, 'date': '03/22', 'time': '08:51:06', 'type': 'INFO', 'line': ':...read_physical_netif: index #1, interface TR1 has address 9.37.65.139, ifidx 1'}
"""

03-read.py

import csv
with open("country.csv", "r") as file:
    csv_reader = csv.reader(file)
    for line in csv_reader:
        print(line)
"""
# Output
['name', 'area', 'country_code2', 'country_code3']
['Afghanistan', '652090.00', 'AF', 'AFG']
['Albania', '28748.00', 'AL', 'ALB']
...
"""

04-read.py

import csv
rows = []
with open("country.csv", "r") as file:
    csv_reader = csv.DictReader(file)
    for row in csv_reader:
       rows.append(row)
print(rows[2])
"""
# Output
{'name': 'Algeria', 'area': '2381741.00', 'country_code2': 'DZ', 'country_code3': 'DZA'}
"""

05-read.py

import csv
import io
from typing import Any
from urllib.request import urlopen
oscar_age_female_url = (
    "https://people.sc.fsu.edu/~jburkardt/data/csv/oscar_age_female.csv"
)
def requestCSV(url: str, default: list[Any] = []) -> list[dict[str, str]]:
    ## A function take url to read csv file and
    ## return list of dictionary rows in it
data = default
    with urlopen(url) as response:
        ## Open an html url
io_reader = io.StringIO(response.read().decode())
reader = csv.reader(io_reader, skipinitialspace=True)
        ## Read csv and convert to dictionary, strip extra space
        for row in reader:
            data.append(row)
    return data
rows = requestCSV(oscar_age_female_url)
print(rows[0])  ## Headers
print(rows[1:3])  ## 2,3 rows
"""
# Output
['Index', 'Year', 'Age', 'Name', 'Movie']
[
  ['1', '1928', '22', 'Janet Gaynor', 'Seventh Heaven, Street Angel and Sunrise: A Song of Two Humans'], 
  ['2', '1929', '37', 'Mary Pickford', 'Coquette']
]
"""

06-read.py

import csv
import io
from typing import Any
from urllib.request import urlopen
oscar_age_female_url = (
    "https://people.sc.fsu.edu/~jburkardt/data/csv/oscar_age_female.csv"
)
def requestJsonCSV(url: str, default: list[Any] = []) -> list[dict[str, str]]:
    ## A function take url to read csv file and
    ## return list of dictionary rows in it
data = default
    with urlopen(url) as response:
        ## Open an html url
io_reader = io.StringIO(response.read().decode())
reader = csv.DictReader(io_reader, skipinitialspace=True)
        ## Read csv and convert to dictionary, strip extra space
for row in reader:
            data.append(row)
    return data
rows = requestJsonCSV(oscar_age_female_url)
print(rows[-2:])
"""
# Output
[
  {'Index': '88', 'Year': '2015', 'Age': '54', 'Name': 'Julianne Moore', 'Movie': 'Still Alice'},
  {'Index': '89', 'Year': '2016', 'Age': '26', 'Name': 'Brie Larson', 'Movie': 'Room'}
]
"""

07-read.py

import sqlite3
rows = []
with sqlite3.connect("test.db") as db:
    for row in db.execute(
        "SELECT name, cast(population as unsigned) \
        FROM cities \
        ORDER BY cast(population as unsigned) DESC"
    ):
        rows.append(row)
print(rows[:3])
"""
[('Albuquerque', 448607), ('Arlington', 332969), ('Anaheim', 328014)]
"""
## most populated city
print(rows[0])
"""
('Albuquerque', 448607)
"""

app.log

03/22 08:51:06 TRACE  :...read_physical_netif: Home list entries returned = 7
03/22 08:51:06 INFO   :...read_physical_netif: index #0, interface VLINK1 has address 129.1.1.1, ifidx 0
03/22 08:51:06 INFO   :...read_physical_netif: index #1, interface TR1 has address 9.37.65.139, ifidx 1
03/22 08:51:06 INFO   :...read_physical_netif: index #2, interface LINK11 has address 9.67.100.1, ifidx 2
03/22 08:51:06 INFO   :...read_physical_netif: index #6, interface LOOPBACK has address 127.0.0.1, ifidx 0
03/22 08:51:06 INFO   :...mailbox_register: mailbox allocated for timer

cities.csv

country.csv

sql_import.bash

$ sqlite3 test.db ## Open sqlite with database name
sqlite> .mode csv
sqlite> .import path_to/cities.csv cities
sqlite> .schema
## verify
CREATE TABLE IF NOT EXISTS "cities"(
  "name" TEXT,
  "population" TEXT
);
sqlite> select * from cities;