# io.py
'''
A few ways on how to format output and handle files (read/write).
'''

#
# String output.
#

# Standard string output.
print("Hello World!")

# Convert objects into strings. E.g. numbers.
my_string = "number = " + str(4)

# str uses the __str__ method of the object.
a = 5
my_string = "number = " + a.__str__())

# Alternative function: repr().
my_string = "number = " + repr(4)

# For fancier output we can use the string method 'format'.
print("number = {0}".format(3.2))
print('We are the {} who say "{}!"'.format('knights', 'Ni'))
print("a = {0}, b = {1}".format(5, 6))
print("a = {a}, b = {b}".format(a=5, b=6))

# Greater control using the colon :.
print('The value of PI is approximately {0:.3f}.'.format(np.pi))
print("number = {0:3.2e}".format(123456.123456789))
name = "Pete"
phone = 12345
print('{0:10} ==> {1:10d}'.format(name, phone))

# Find first occurrence of substring.
"Python".find('th')

# Find and replace all occurrences of substring.
"Hello World!".replace('World', 'Python')

# Split the string at specified character.
'1,2,3'.split(',')

# Check starting substring.
"Hello".startswith('He')

# Swap case.
"Hello".swapcase()



#
# Files: read/write.
#

# Open file.
my_file = open('time_series.dat', 'r')
# The second argument specifies the options:
# r: read
# w: write
# a: append
# b: binary
# Mind the order: 'wr', 'br', 'ar', not 'rw', 'rb', 'ra'.

# Read the entire file or a specified length.
my_file = open('test_file', 'r')
print(my_file.read(10))
print(my_file.read())

# Find current location in file.
my_file.tell()

# Specify location in file.
my_file.seek(5)

# Close the file.
my_file.close()

# Read only one line.
my_file.readline()

# Read all the lines.
print(my_file.readlines())

# Loop over lines in the file.
for line in my_file:
    print(line)

# Writing into a file requires to open it with the 'w' or 'a' option.
my_file.write("some string")