Creating list out of the first letter of every word in a string

[volcano63]

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This is list comprehension format. In the Udemy course I’m taking, the original task was to use list comprehension but I find it hard to read so I decided to complete the exercise without list comprehension by just using a regular for loop.

List comprehension is fundamental to mastering Python. Maybe that definition will help - list comprehension is a drill-down of a regular loop where the value appended to the list is placed before the loop.

Take a look at this example - building a list of even values from a list of numbers. This is how you will do it in a loop

evens = []
for num in num_list: # <---- loop expression
    if num % 2 == 0: # <---- condition (predicate)
        evens.append(num) # <---- appended value

And now pay attention to the list comprehension form - same code sans columns, just the value moved before the loop.

evens = [
num # <---- appended value
for num in num_list # <---- loop expression
    if num % 2 == 0 # <---- condition (predicate)
]

Is it easier now?

The first search result when you Google, ‘python adding to a list’, is an official doc by Google titled, “Python Lists”. It’s helpful but there is one recurring theme through out the doc which to me looks like an enormous mistake. Take a look at this teachable code snippet from that webpage:

list = ['larry', 'curly', 'moe']
list.append('shemp')         ## append elem at end
list.insert(0, 'xxx')        ## insert elem at index 0
list.extend(['yyy', 'zzz'])  ## add list of elems at end
print list  ## ['xxx', 'larry', 'curly', 'moe', 'shemp', 'yyy', 'zzz']
print list.index('curly')    ## 2

In every single line, the author of the doc creates or refers to a variable named, list. What doesn’t make sense to me is that list is a reserved keyword in Python in general, correct?

Actually, list is a built-in function (good catch) so naming a variable list shadows that function (you cannot assign a value to a keyword).

Not everything you find on the web is of good quality, and sometimes shitty resources hide behind a great name. This resource - besides teaching bad practice - is also pitifully outdated - Python2. I usually use time filter in my searches - that helps.

The last but not the least - functional programming version of solution

Output:
In [2]: from operator import itemgetter

In [3]: list(map(itemgetter(0), mystring.split()))
Out[3]: ['S', 'a', 'a', 's', 'g', 'a', 's', 'h']

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Wow, this developers.google.com crap is actually

Last updated May 18, 2018.