read files python code example
Example 1: python read file line by line
with open("file.txt") as file_in:
lines = []
for line in file_in:
lines.append(line)Example 2: python read file
with open("file.txt", "r") as txt_file:
return txt_file.readlines()Example 3: python read file
# Basic syntax:
with open('/path/to/filename.extension', 'open_mode') as filename:
file_data = filename.readlines() # Or filename.read()
# Where:
# - open imports the file as a file object which then needs to be read
# with one of the read options
# - readlines() imports each line of the file as an element in a list
# - read() imports the file contents as one long new-line-separated
# string
# - open_mode can be one of:
# - "r" = Read which opens a file for reading (error if the file
# doesn't exist)
# - "a" = Append which opens a file for appending (creates the
# file if it doesn't exist)
# - "w" = Write which opens a file for writing (creates the file
# if it doesn't exist)
# - "x" = Create which creates the specified file (returns an error
# if the file exists)
# Note, "with open() as" is recommended because the file is closed
# automatically so you don't have to remember to use file.close()
# Basic syntax for a delimited file with multiple fields:
import csv
with open('/path/to/filename.extension', 'open_mode') as filename:
file_data = csv.reader(filename, delimiter='delimiter')
data_as_list = list(file_data)
# Where:
# - csv.reader can be used for files that use any delimiter, not just
# commas, e.g.: '\t', '|', ';', etc. (It's a bit of a misnomer)
# - csv.reader() returns a csv.reader object which can be iterated
# over, directly converted to a list, and etc.
# Importing data using Numpy:
import numpy as np
data = np.loadtxt('/path/to/filename.extension',
delimiter=',', # String used to separate values
skiprows=2, # Number of rows to skip
usecols=[0,2], # Specify which columns to read
dtype=str) # The type of the resulting array
# Importing data using Pandas:
import pandas as pd
data = pd.read_csv('/path/to/filename.extension',
nrows=5, # Number of rows of file to read
header=None, # Row number to use as column names
sep='\t', # Delimiter to use
comment='#', # Character to split comments
na_values=[""]) # String to recognize as NA/NaN
# Note, pandas can also import excel files with pd.read_excel()Example 4: read file python
document = 'document.txt'
file = open(document, 'r')
# 'r' can be replaced with:
# 'w' to write
# 'a' to append (add to the end)
# 'w+' makes a new file if one does not already exist of that name
# 'a+' is the same as 'w+' but it appends if the file does exist
##go to beginning of document
file.seek(0)
##print all lines in document, except empty lines:
for i in file:
k = i.strip()
print k
##close the file after you are done
file.close()
##this can temporarily open a file:
with open(document) as ur:
for i in ur:
k = i.strip()
print kExample 5: open text file in python
f=open("Diabetes.txt",'r')
f.read()Example 6: python open file
with open('filename', 'a') as f: # able to append data to file
f.write(var1) # Were var1 is some variable you have set previously
f.write('data')
f.close() # You can add this but it is not mandatory
with open('filename', 'r') as f: # able to read data from file ( also is the default mode when opening a file in python)
with open('filename', 'x') as f: # Creates new file, if it already exists it will cause it to fail
with open('filename', 't') as f: # opens the file in text mode (also is defualt)
with open('filename', 'b') as f: # Use if your file will contain binary data
with open('filename', 'w') as f: # Open file with ability to write, will also create the file if it does not exist (if it exists will cause it to fail)
with open('filename', '+') as f: # Opens file with reading and writing
# You can combine these as you like with the + for reading and writing