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How to install Xcode Command Line Tools
How do I get the command-line build tools installed with the current Xcode/Mac OS X v10.8 (Mountain Lion) or later?
13 Answ...
PHP: exceptions vs errors?
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Exceptions are thrown - they are intended to be caught. Errors are generally unrecoverable. Lets say for instance - you have a block of code that will insert a row into a database. It is possible that this call fails (duplicate ID) - you will want to have a "Error" which in this case is an "Exc...
Can someone explain the traverse function in Haskell?
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traverse is the same as fmap, except that it also allows you to run effects while you're rebuilding the data structure.
Take a look at the example from the Data.Traversable documentation.
data Tree a = Empty | Leaf a | Node (Tree a) a (Tree a)
The Functor instance of Tr...
List comprehension: Returning two (or more) items for each item
...bda x: x + 2
>>> g = lambda x: x ** 2
>>> list(chain.from_iterable((f(x), g(x)) for x in range(3)))
[2, 0, 3, 1, 4, 4]
Timings:
from timeit import timeit
f = lambda x: x + 2
g = lambda x: x ** 2
def fg(x):
yield f(x)
yield g(x)
print timeit(stmt='list(chain.from_itera...
Why do we use __init__ in Python classes?
...Spot is a bit of a cripple and is mostly yellow. The __init__ function is called a constructor, or initializer, and is automatically called when you create a new instance of a class. Within that function, the newly created object is assigned to the parameter self. The notation self.legs is an attrib...
Get difference between two lists
...hat this only returns the temp1-temp2? .. As other said in order to return all the differences you have to use the sysmetric difference: list(set(temp1) ^ set(temp2))
– rkachach
Feb 16 '16 at 16:00
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How to set custom favicon in Express?
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In Express 4
Install the favicon middleware and then do:
var favicon = require('serve-favicon');
app.use(favicon(__dirname + '/public/images/favicon.ico'));
Or better, using the path module:
app.use(favicon(path.join(__dirname,'public','ima...
Convert floats to ints in Pandas?
... If it's dtype then you need to create those columns as dtype object so it allows mixed, otherwise my advice would be to just use float and when doing comparisons use np.isclose
– EdChum
Jun 7 '19 at 7:46
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Uninstall Node.JS using Linux command line?
How do you uninstall node.js using the cmd line in linux?
14 Answers
14
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Get the first element of each tuple in a list in Python [duplicate]
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Use a list comprehension:
res_list = [x[0] for x in rows]
Below is a demonstration:
>>> rows = [(1, 2), (3, 4), (5, 6)]
>>> [x[0] for x in rows]
[1, 3, 5]
>>>
Alternately, you could use unpacking instead of x[0]:
res_li...