Answers for "how to open a file and read it in python"

python read file

with open("file.txt", "r") as txt_file:
  return txt_file.readlines()

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()

how to read files in python with

def file_reader(file):
    with open(file,'r') as infile:
        table = [row for row in infile]
    return table
print(file_reader('file.txt'))

python open file

def main():
    f= open("guru99.txt","w+")
    #f=open("guru99.txt","a+")
    for i in range(10):
         f.write("This is line %drn" % (i+1))
    f.close()
    #Open the file back and read the contents
    #f=open("guru99.txt", "r")
    #if f.mode == 'r':
    #   contents =f.read()
    #    print (contents)
    #or, readlines reads the individual line into a list
    #fl =f.readlines()
    #for x in fl:
    #print(x)
if __name__== "__main__":
  main()

how to read a file in python

# when you want to read the file from terminal in python use 
import sys
f = open(sys.argv[1])
line=f.readline()