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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...
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...
wkhtmltopdf: cannot connect to X server
...ble, so no need to make the wrapper script.
– jeffery_the_wind
Mar 13 '12 at 13:43
it worked for me.. in some situatio...
Fastest method to replace all instances of a character in a string [duplicate]
What is the fastest way to replace all instances of a string/character in a string in JavaScript? A while , a for -loop, a regular expression?
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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...
What is the difference between dict.items() and dict.iteritems() in Python2?
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It's part of an evolution.
Originally, Python items() built a real list of tuples and returned that. That could potentially take a lot of extra memory.
Then, generators were introduced to the language in general, and that method was reimplemented as an ite...
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...
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...
How to read keyboard-input?
... mixing different Pythons here (Python 2.x vs. Python 3.x)...
This is basically correct:
nb = input('Choose a number: ')
The problem is that it is only supported in Python 3. As @sharpner answered, for older versions of Python (2.x), you have to use the function raw_input:
nb = raw_input('Choose...
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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