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I've made this list; each item is a string that contains commas (in some cases) and colon (always):
dinner = [
'cake,peas,cheese : No',
'duck,broccoli,onions : Maybe',
'motor oil : Definitely Not',
'pizza : Damn Right',
'ice cream : Maybe',
'bologna : No',
'potatoes,bacon,carrots,water: Yes',
'rats,hats : Definitely Not',
'seltzer : Yes',
'sleeping,whining,spitting : No Way',
'marmalade : No'
]
I would like to create a new list from the one above as follows:
['cake : No',
'peas : No',
'cheese : No',
'duck : Maybe',
'broccoli : Maybe',
'onions : Maybe',
'motor oil : Definitely Not',
'pizza : Damn Right',
'ice cream : Maybe',
'bologna : No',
'potatoes : Yes',
'bacon : Yes',
'carrots : Yes',
'water : Yes',
'rats : Definitely Not',
'hats : Definitely Not',
'seltzer : Yes',
'sleeping : No Way',
'whining : No Way',
'spitting : No Way',
'marmalade : No']
But I'd like to know if/ how it's possible to do so in a line or two of efficient code employing primarily Python's higher order functions. I've been attempting it:
reduce(lambda x,y: x + y, (map(lambda x: x.split(':')[0].strip().split(','), dinner)))
...produces this:
['cake',
'peas',
'cheese',
'duck',
'broccoli',
'onions',
'motor oil',
'pizza',
'ice cream',
'bologna',
'potatoes',
'bacon',
'carrots',
'water',
'rats',
'hats',
'seltzer',
'sleeping',
'whining',
'spitting',
'marmalade']
...but I'm struggling with appending the piece of each string after the colon back onto each item.
897
In this article, we want to focus our discussion on three commonly used higher-order functions, namely map (), filter (), and reduce (). The first function that we’re discussing is the map () function, which has the following general format: map (mapping_function, *iterables).
You can pass a method to a higher order function just like you would any function, you just have to pass it as object.method:
The map () function returns a map object, which is not a list object. We use the string’s built-in function upper as the mapping function. We use the list () constructor to create a list from the map object. In addition to the use of the built-in function, we can declare a function ourselves as the mapping function.
Higher-order functions are functions that take a function as a parameter and/or return a function as an output. A few useful higher-order functions are map (), filter (), and reduce (). map () and filter () are built-in functions, whereas reduce () is contained in functools () module.
I would create a dict using, zip, map and itertools.repeat:
from itertools import repeat
data = ({k.strip(): v.strip() for _k, _v in map(lambda x: x.split(":"), dinner)
for k, v in zip(_k.split(","), repeat(_v))})
from pprint import pprint as pp
pp(data)
Output:
{'bacon': 'Yes',
'bologna': 'No',
'broccoli': 'Maybe',
'cake': 'No',
'carrots': 'Yes',
'cheese': 'No',
'duck': 'Maybe',
'hats': 'Definitely Not',
'ice cream': 'Maybe',
'marmalade': 'No',
'motor oil': 'Definitely Not',
'onions': 'Maybe',
'peas': 'No',
'pizza': 'Damn Right',
'potatoes': 'Yes',
'rats': 'Definitely Not',
'seltzer': 'Yes',
'sleeping': 'No Way',
'spitting': 'No Way',
'water': 'Yes',
'whining': 'No Way'}
Or using the dict constructor:
from itertools import repeat
data = dict(map(str.strip, t) for _k, _v in map(lambda x: x.split(":"), dinner)
for t in zip(_k.split(","), repeat(_v)))
from pprint import pprint as pp
pp(data)
If you really want a list of strings, we can do something similar using itertools.chain and joining the substrings:
from itertools import repeat, chain
data = chain.from_iterable(map(":".join, zip(_k.split(","), repeat(_v)))
for _k, _v in map(lambda x: x.split(":"), dinner))
from pprint import pprint as pp
pp(list(data))
Output:
['cake: No',
'peas: No',
'cheese : No',
'duck: Maybe',
'broccoli: Maybe',
'onions : Maybe',
'motor oil : Definitely Not',
'pizza : Damn Right',
'ice cream : Maybe',
'bologna : No',
'potatoes: Yes',
'bacon: Yes',
'carrots: Yes',
'water: Yes',
'rats: Definitely Not',
'hats : Definitely Not',
'seltzer : Yes',
'sleeping: No Way',
'whining: No Way',
'spitting : No Way',
'marmalade : No']
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