***I'm not explaining this well so hopefully this edit makes more sense: basically I have to write code that will work for a ton of test cases, the input below is just an example. So I can't manually enter the input into my function
Say I have the following input:
0
4
0,2,2,3
and I need to generate some sort of output like
1
How can I do this?
What I mean is, if I'm normally given a problem, I can just define a function and then input the values manually, but how do I read raw data (perform a series of functions/operations on the data)?
(For the assignment I am supposed to receive input on STDIN -> and print correct output on STDOUT
STDIN is just a file (or a file-like object) represented by sys.stdin; you can treat it like a normal file and read data from it. You can even iterate over it; for example:
sum = 0
for line in sys.stdin:
item = int(line.strip())
sum += item
print sum
or just
entire_raw_data = sys.stdin.read()
lines = entire_raw_data.split()
... # do something with lines
Also, you can either iteratively call raw_input() which returns successive lines sent to STDIN, or even turn it into an iterator:
for line in iter(raw_input, ''): # will iterate until an empty line
# so something with line
which is equivalent to:
while True:
line = raw_input()
if not line:
break
# so something with line
See also: https://en.wikibooks.org/wiki/Python_Programming/Input_and_output
We can easily use raw_input() for this case:
text_input = raw_input("Enter text:")
If you're using Python 3, you can use input() in the same way:
text_input = input("Enter text:")
Or, if you prefer to run your program with command line arguments, use sys.argv
import sys
for i in sys.argv:
if i >= 1:
command = i
#do something with your command
Here is a good read: http://www.linuxtopia.org/online_books/programming_books/python_programming/python_ch06s03.html
EDIT
Okay, just understand the real question here.
The simple way: you store the data in a text file, and read it with your program.
f = open("path/to/command.txt", 'r')
commmands = f.read()
This way you can process your data quickly. After processed, you can write it down to another file:
output_file = open("path/to/output.txt", 'w')
output_file.write(result)
As what to do with your command file, you can structure it yourself and process it with str.split() method, and loop through it.
Tips: So you don't forget to close the file, it is recommended to use the with statement:
with open('file.txt', 'w') as f:
#do things
f.write(result)
More on file processing:
http://docs.python.org/3.3/tutorial/inputoutput.html#reading-and-writing-files
Hope that helps!
You can use the function raw_input() to read from the standard input and then process as you need.
use this raw_input() it's the basic python input function.
myInput = raw_input()
for more information about raw input please refer to:
http://docs.python.org/2/library/functions.html#raw_input
Usually you want to do:
the_input = input(prompt) # Python 3.x
or
the_input = raw_input(prompt) # Python 2.x
And then:
print(output) # Python 3.x
or
print output # Python 2.x
However, you can also (but probably don't want to) do this:
import sys
the_input = sys.stdin.readline()
bytes_written = sys.stdout.write(output)
This is more or less what print and input do behind the scenes. sys.stdin, sys.stdout (and sys.stderr) work just like files - you can read and write to them etc. In Python terminology they are known as file-like objects.
From what I understand, you want something like this:
def f(x, y, z):
return 2*x + y + z + 1
a = int(input("Enter a number: ")) # presuming Python 3.x
b = int(input("Enter another number: "))
c = int(input("Enter the final number: "))
print(f(a, b, c))
If run, that would look something like this:
>>> Enter a number: 7
>>> Enter another number: 8
>>> Enter the final number: 9
>>> 32
