I recieved a new laptop and the Python certificates were failing for me. The quickest, but not necessarily the most secure method for fixing this is to either use the –trusted-host entry for each host that throws a certificate exception or to create a file in the ~/.config/pip/pip.conf file like the one below. This covers the main sites that pip uses to install packages.

[global]
trusted-host = pypi.python.org
               pypi.org
               files.pythonhosted.org

When I develop in the web, there are plenty of times that I want to see information about where I am in the program or what is going on in the Javascript when I load the page. I use the Console to watch updates but it can be difficult to read when you have possibly hundreds of log statements.
Usually you can just use the standard console.log function:

> console.log("Some information");
Some information
or 

> console.debug("Some information");
Some information

or 

> console.info("Some information");
Some information

You also get the line number and file that the output comes from in the console.

But did you know that you can use the following:

console.clear()
console.error(object)
console.table(array)
console.warn()

Let’s say you want to clear the current console. You can place in your code, or use it within the console itself.

console.clear();

Or you can get color coded lines with the warn or error functions:

> console.warn("This is a warning");

> console.error("Error: Danger");

And if you need to display an array that and want a better layout use console.table():
> console.table(['a','b','c']);

I was talking to a friend of mine on the phone the other day and we were talking about how debugging in Chrome was sometimes frustrating. We both had some ideas on how that could have been made better for each of us.

While you can load your page, find the line of code, and add a set of breakpoints. He let me know kicking off the debugger in a certain part of your code just by adding the following line of code where you want the code to stop:

debugger;

Once this brings up the debugging window, this behaves like a breakpoint and stops execution. Now you can see the value of your variables, or you can step through the rest of your code line by line.

My next post will talk about the different kind of console logging functions that are availabole.

I have been working to up my skills in the web development arena and have to say that The Odin Project is a great place to get started. The lesson plan directs you to not just learn the different languages required to create for the web, but also what is going on in the computer when you do things. It also gives you information about how to connect with other developers and how to progress your skills.

Some of the projects teach you to create images with a group of divs and pure CSS like this example of the Dancing Android character.

Also learning to re-create the basic display of the Google Home Page helps to learn styling techniques, using sprites and how to position objects.

Some of the best ways to learn HTML design are to take a web page that you like and try to re-create it without looking at the styling. Once you have a good approximation, see where you differed from the original.

I have had to process data files from customers that have come in as delimited files. The files are usually in CSV formats and the delimiters might change depending on the content of the files. Sometimes the delimiters are usually tabs”t”, pipes “|”, comma “,” or semi-colon “;”. A useful tool for processing this type of file is to use awk.

Example command line:

awk -F 't' '{OFS="|"; if (NR != 1) print $3,$2,$1}'

The ‘-F’ argument is followed by the character that you have the file separated on. The example above uses a tab escape sequence ‘t’ but you could have any character. One potential problem is if the data contains the same character that you are attempting to split on. As in a comma separated list using commas within a long text sequence.
The Second sequence of quoted text above starts the processing of the file. The if statement uses the NF keyword which stands for Number of Row. This tells the script that it should not fire for the first row. The print statement allows you to pick and choose the columns(numbered from 1) to use or allows you to reorder them.
The ‘OFS’ part of the command line that helps with the print statement describes the Output Field Separator. In the case above it is using a pipe character ‘|’ to separate the text as it is being printed out. This allows you comma separate the fields that you want instead of having to use a more sophisticated printf statement.

The input file is of the form

Label,name,address

And the output is going to be of the form:

address,name,Label

Here is my basic script for handling command line arguments in Python(pre version 2.7 when optparse
was deprecated). The optparse library is very useful in not only handling the command line
arguments, but setting up your help menu as well.

You will need to create an OptionParser and the usage argument lets you print the usage statement
for the script. Then you can add options, add groups for options or collect the left over
parameters as a secondary command or list of files. I use this method often as I create scripts
that help automate build processes.

#!/usr/bin/python

import sys, optparse

# This creates an OptionParser object with the usage string.
op = optparse.OptionParser(usage=" %prog [options]")
# This will add an option -m or --mode which takes sets the mode variable as
# True or False
op.add_option("-m","--mode",help="Specify the mode for the command", 
            action="store_true", dest="mode",default=False)
# This parses the options and places the selected options above in the _options
# object and the rest in arguments.
_options,arguments = op.parse_args()

# Checks if no arguments are passed and if so, runs the print_help method of 
# the OptionParser object
if len(sys.argv) == 1:
    op.print_help()

# This was just to show what happened when you did or didn't pass the
# --mode argument.
if  _options.mode:
    print "Mode is on"
else:
    print "Mode is off"

This method is currently deprecated as of version 2.7. I will write a follow-up post that uses
the newer argparse routine to highlight any differences.

Tags: Python, scripting

When I am writing build automation scripts, there are times that I have to insure that the previous command completed
with no errors. I have found that ERRORLEVEL gets filled in with the return value from a command.

dir %1

if (%ERRORLEVEL%) == (0) echo Found File: %1
if (%ERRORLEVEL%) == (1) echo Missing File: %1

So if you save the previous in a file and run the command with one (1) argument, it will display the output of the dir command
but also print either “Found file: ” or “Missing File: “.

Tags: DOS, scripting

I was writing a basic guessing game and when I tried to take user input I was
getting the following:

Code:

guess = input()
d

Error:

Traceback (most recent call last):
  File "", line 1, in 
  File "", line 1, in 
NameError: name 'd' is not defined

The problem is actually with the version of Python that I was using. If you
are using Python 2.x, you need to use the raw_input() function. And with 3.x
you can use the input() function.

Tags: Python, scripting

There comes a time when you are writing a program and you need to branch based on input to a program.
This is the format of the if/else statement in Python.

if <some true/false statement> :
  <some statements that run if the if statement is true>
else:
  <some other statements that run if the if statement are false>  

There may be times when you have more than one value set to test against. In that case you can write a many if/else
statements but you can chain the if/else statements with an elif. So the chain becomes if/elif/else.

if x < 5:
  <some statements that run if the if statement is true>
elif x > 5 and x < 10:
  <some statements that run if the elif statement is true>
else:
  <if none of the if checks are true, run the statements in the else case.>

Tags: Python, scripting

I was toying with a prime number finder and was creating a set of if/else statements for a horribly failed attempt
and wanted to skip to the next number on any of the if statements that were true. I didn’t want to put an empty print
statement as that would disrupt the output I was expecting from the program. I found the pass statement.
Here is an example from my not very successful attempt at finding primes:

if inp > 2 and inp % 2 == 0:
  pass
elif inp > 3 and inp % 3 == 0:
  pass
elif inp > 7 and inp % 7 == 0:
  pass
elif inp > 9 and inp % 9 == 0:
  pass
else:
  print inp, " is a prime"

Yes, this does not accurately find the primes, but it would skip any number that is divisible by 2,3,5,7, or 9. And
anything that does not match this will be listed as a prime, this is incorrect and would be made to add new elif
statements as each prime was found.

Tags: Python, scripting