How to merge a branch in git

Follow the commands below to do the auto merge the branch in git:

$ git checkout -b {new-branch-name}

$ git merge --no-ff {old-branch-name}

$ git push -u origin {new-branch-name}

Concatenating and combining lists in Python

CODE:

[4, None, 'foo'] + [7, 8, (2, 3)]

or

x = [4, None, 'foo']

x.extend([7, 8, (2, 3)])

print(x)

OUTPUT:

[4, None, 'foo', 7, 8, (2, 3)]

Ternary expressions in Python

A ternary expression in Python allows you to combine an if-else block that produces

a value into a single line or expression. The syntax for this in Python is:

value = true-expr if condition else false-expr

Here, true-expr and false-expr can be any Python expressions. It has the identical

effect as the more verbose:

if condition:

    value = true-expr

else:

    value = false-expr

This is a more concrete example:

CODE:

x = 5

'Non-negative' if x >= 0 else 'Negative'

OUTPUT:

'Non-negative'

What is pass in Python

pass is the "no-op" statement in Python. It can be used in blocks where no action is to

be taken (or as a placeholder for code not yet implemented); it is only required

because Python uses whitespace to delimit blocks:

Eg:

if x < 0:

    print('negative!')

elif x == 0:

    # TODO: put something smart here

    pass

else:

    print('positive!')

How to chain comparisons in Python

CODE:

print(4 > 3 > 2 > 1)

OUTPUT:

True

What are the datetime format specifications (ISO C89 compatible) in Python

Below are the Datetime format specification (ISO C89 compatible) in Python:

Why triple quotes (" " ") are used in Python

For multiline strings with line breaks, you can use triple quotes, either ''' or " " ":

c = """

This is a long string that

spans multiple lines

"""

Standard Python scalar types

Below are the standard Python scalar types:

Type: Description

None: The Python "null" value (only one instance of the None object exists)

str: String type; holds Unicode (UTF-8 encoded) strings

bytes: Raw ASCII bytes (or Unicode encoded as bytes)

float: Double-precision (64-bit) floating-point number (note there is no separate double type)

bool: A True or False value

int: Arbitrary precision signed integer

How to check/get/set an attribute or a method in Python (Reflection)

Python allows an easy way to check whether an object contains/has an attribute or method with the specified name as follows:

1) getattr:

Gets the attribute/method with the specified name, usage as follows:

usage: getattr(obj, 'method/attribute name')

eg: 

a='RK'; 

getattr(a, 'split')

2) hasattr:

Checks whether object has the attribute/method with the specified name, usage as follows:

usage: hasattr(obj, 'method/attribute name')

eg: 

a='RK'; 

hasattr(a, 'split')

3) setattr:

Sets the attribute/method with the specified name, usage as follows:

usage: setattr(obj, 'method/attribute name', value)

eg: 

a=Employee(23)

setattr(a, 'id', 45)

Python assignments are by references

When assigning a variable (or name) in Python, you are creating a reference, have a look at below:

CODE:

a=[1,2]

b=a

print("Before append: ", b)

b.append(3)

print("Shows a & b are same references, after append to b, a: ", a)

OUTPUT:

Before append:  [1, 2]

Shows a & b are same references, after append to b, a:  [1, 2, 3]