Programming in Python

[01BTC10]

By the way there is a computer networks course starting in 3 months: https://www.coursera.org/course/comnetworks

Course Syllabus:
Introduction, Protocols and Layering
Physical and Link layers
Retransmissions, Multiple access, Switching
Network layer, Internetworking
Intra- and Inter-domain Routing
Transport layer, Reliability
Congestion Control
DNS, Web/HTTP, Content Distribution
Quality of Service and Real-time Apps
Network Security

[gangplank]

Yep you got it
Just two remarks: do you know you can "print cm_to_inches(1.0)" directly? And why writing ones in the formulas? Why not just "cm=2.54*inch"?

The example used in the course is fahrenheit to celsius but I couldn't seem to grasp it. I tried thinking of a few different ways I might use a function and those are just the things that came to mind. Obviously they are not useful as you've provided better options but for the purposes of understanding how a function operates, it seems to have worked for me

[gangplank]

Is this about right for creating a function and then creating another which calls the previous function?

http://www.codeskulptor.org/#user19_v3vzRwYgMq_1.py

[01BTC10]

Is this about right for creating a function and then creating another which calls the previous function?

http://www.codeskulptor.org/#user19_v3vzRwYgMq_1.py

You can call a function anywhere you want in your code, even inside another function.

[jambola2]

I recommend trying a guide called learn python the hard way.
It is really helpful and easy.

[FirstAscent]

Working on the functions lesson at the moment, I didn't really understand it at first. I think I've got it now as I tried to write some of my own and it outputs the correct answer. Maybe someone can check that my thinking is right on these functions I wrote.

# converts cm to inches

def cm_to_inches(cm):
    inch = 1 / 2.54 * cm
    return inch

a1 = cm_to_inches(25.4)
print a1

Less lines are better when it doesn't reduce clarity. The reason is it allows more lines visible on the screen, which allows greater comprehension while examining the code. But don't sacrifice white space to achieve that.

def cm_to_inches(cm):
    return cm / 2.54

And there's no point in dividing by 1 or multiplying by 1 or zero when they are constants:

# convert inches to cm

def inch_to_cm(inch):
    cm = 2.54 / 1 * inch
    return cm

Try this:

def inch_to_cm(inch):
    return inch * 2.54

[01BTC10]

Nice  

Code:

def miles_to_km(miles):
    return miles * 1.60934

def km_to_miles(km):
    return km / 1.60934

print miles_to_km(10)
print km_to_miles(16.0934)

Edit:
Improved version that assumes that the user only input numbers:

Code:

def miles_to_km(miles):
    return float(miles) * 1.60934

def km_to_miles(km):
    return float(km) / 1.60934

miles_input = input('Please input miles to convert in km:')
print miles_input + " miles = " + str(miles_to_km(miles_input)) + " km"

km_input = input('Please input km to convert in miles:')
print km_input + " km = " + str(km_to_miles(km_input)) + " miles"

[FirstAscent]

An integer multiplied by a float returns a float. Since 1.60934 is a float, even if miles is an integer, the result will be a float.

[01BTC10]

An integer multiplied by a float returns a float. Since 1.60934 is a float, even if miles is an integer, the result will be a float.

If miles == 1 with this code:

Code:

def miles_to_km(miles):
    return miles * 1.60934

It prints "11"  

If use this line:

Code:

def miles_to_km(miles):
    return float(miles) * 1.60934

The answer is correct.

[FirstAscent]

An integer multiplied by a float returns a float. Since 1.60934 is a float, even if miles is an integer, the result will be a float.

If miles == 1 with this code:

Code:

def miles_to_km(miles):
    return miles * 1.60934

The answer is "11"  

If use this line:

Code:

def miles_to_km(miles):
    return float(miles) * 1.60934

The answer is correct.

This program prints 1.60934.

Code:

def miles_to_km(miles):
    return miles * 1.60934

print miles_to_km(1) 

Show me your entire program here.

[01BTC10]

An integer multiplied by a float returns a float. Since 1.60934 is a float, even if miles is an integer, the result will be a float.

If miles == 1 with this code:

Code:

def miles_to_km(miles):
    return miles * 1.60934

The answer is "11"  

If use this line:

Code:

def miles_to_km(miles):
    return float(miles) * 1.60934

The answer is correct.

This program prints 1.60934.

Code:

def miles_to_km(miles):
    return miles * 1.60934

print miles_to_km(1) 

Show me your entire program here.

http://www.codeskulptor.org/#user19_9Zu5nZ2ctm_3.py

I think it's because that I convert a string to a float. It is not integer --> float.

[FirstAscent]

I'm pretty sure I know what your problem is. First, what version of Python are you using. Type python at the command prompt.

[FirstAscent]

Everything I said is correct.

You're writing bad code. Here is a fixed version of your code:

Code:

def miles_to_km_no_float(miles):
    return miles * 1.60934

def miles_to_km_with_float(miles):
    return float(miles) * 1.60934

miles_input=input('Please input miles to convert in km:')
print str(miles_input) + " miles = " + str(miles_to_km_no_float(miles_input)) + " km (no float)"

print str(miles_input) + " miles = " + str(miles_to_km_with_float(miles_input)) + " km (float)" 

[01BTC10]

I'm pretty sure I know what your problem is. First, what version of Python are you using. Type python at the command prompt.

There is no command prompt. It's a web browser implementation for the course. It works fine with codeskulptor but throw an error with python 2.7.3 on my computer.

Code:

Traceback (most recent call last):
  File "test.py", line 13, in <module>
    print miles_input + " miles = " + str(miles_to_km_no_float(miles_input)) + " km (no float)"
TypeError: unsupported operand type(s) for +: 'int' and 'str'

[FirstAscent]

And that's the problem. Your toy Python interpreter did not catch the problem.

[01BTC10]

Everything I said is correct.

You're writing bad code. Here is a fixed version of your code:

Code:

def miles_to_km_no_float(miles):
    return miles * 1.60934

def miles_to_km_with_float(miles):
    return float(miles) * 1.60934

miles_input=input('Please input miles to convert in km:')
print str(miles_input) + " miles = " + str(miles_to_km_no_float(miles_input)) + " km (no float)"

print str(miles_input) + " miles = " + str(miles_to_km_with_float(miles_input)) + " km (float)" 

It works fine using python on my computer but still get the same old result with codeskulptor.

[FirstAscent]

The problem is not with the functions. This is pointless:

Code:

def miles_to_km_with_float(miles):
    return float(miles) * 1.60934

[01BTC10]

And that's the problem. Your toy Python interpreter did not catch the problem.

I know it's meant to make it easy for student to share the link for their homework but the python implementation lack some feature.

[FirstAscent]

Whatever the case, you don't need to convert your integer to a float in the function, because multiplying it by a float already does that.

Also, I can't get a program to print the Python version to work in the online version.

For example, this does not work:

import platform
print(platform.python_version())

[01BTC10]

Whatever the case, you don't need to convert your integer to a float in the function, because multiplying it by a float already does that.

Also, I can't get a program to print the Python version to work in the online version.

For example, this does not work:

import platform
print(platform.python_version())

I think it's an incomplete version 2.