PythonConcepts.md

split()--->

At some point, you may need to break a large string down

into smaller chunks, or strings. This is the opposite of concatenation

which merges or combines strings into one.

join()--->

The join() is a string method which returns a string concatenated with the elements of an iterable

The join() method takes an iterable - objects capable of returning its members one at a time

Some of the example of iterables are:

Native datatypes - List, Tuple, String, Dictionary and Set

File objects and objects you define with an iter() or getitem() method

It only works on strings and not int or any other data type

tuple=('8','9','3')

print ','.join(tuple)

import math
c=50
h=30
value = []
items=[x for x in raw_input().split(',')]  # user enter a comma separated value
print items            # returns a list
for d in items:
    value.append(str(int(round(math.sqrt(2*c*float(d)/h)))))

print value            # returns a list
print ','.join(value)  #return in comma separated output

2-D Matrix

b= [[i*j for j in range(y)] for i in range(x)]

3-D Matrix

b= [[[i*j*z for j in range(y)] for i in range(x)]for z in range(g)]

ASCII value conversion

ord(<enter the char>)

Sorting without using sorted() in python

a=raw_input("Enter\n")
b=[]

list= [b.append(i) for i in a.split(',') if i not in b]
print b
for i in range(len(b)):
    for j in range(len(b)-1):
        if b[j]>b[j+1]:     #replacing if the condition is true
            b[j],b[j+1]=b[j+1],b[j]
print b

Conversion from Binary to integer and vice-versa

a=(raw_input("Enter\n"))
for i in a.split(','):
    i=int(i,2)  # bin to int
    j=bin(i)   # int to binary
    print j[::2]  # omit the '0b' in the bin converted number
    print i

Check if the character is a letter or a digit

isalpha() ---> The isalpha() returns:

isaplha() doesn't take any inputs

True if all characters in the string are alphabets (can be both lowercase and uppercase).

False if at least one character is not alphabet.

STRING METHODS

str.isaplha()--->

Return true if all characters in the string are alphabetic and there is at least one character, false otherwise

str.isalnum()--->

Return true if all characters in the string are alphanumeric and there is at least one character, false otherwise

A character c is alphanumeric if one of the following returns True: c.isalpha(), c.isdecimal(), c.isdigit(), or c.isnumeric().

str.isdecimal()--->

Return true if all characters in the string are decimal characters and there is at least one character, false otherwise.

ex. "12345½" -->false

str.isdigit()--->

Return true if all characters in the string are digits and there is at least one character, false otherwise.

ex. "12345½"--->false

str.islower()--->

Return true if all cased characters [4] in the string are lowercase and there is at least one cased character, false otherwise.

str.isnumeric--->

Return true if all characters in the string are numeric characters, and there is at least one character, false otherwise

ex. "12345½"---> True

str.strip()--->

strips off the space left and right of the character or end os sentence

str.rstrip()--->

Strips only the right side space only

str.lstrip()---->

Strips off the space on the left side only

Accessing Dictionary

s = raw_input()
d={"UPPER CASE":0, "LOWER CASE":0}
print d["UPPER CASE"]  #you can access a particular value like this
for c in s:
    if c.isupper():
        d["UPPER CASE"]+=1 # incrementing the value
    elif c.islower():
        d["LOWER CASE"]+=1
    else:
        pass
print "UPPER CASE", d["UPPER CASE"] #you can access a particular value
print "LOWER CASE", d["LOWER CASE"]

a=9
n1=int("%s" % a)
print n1
# aa is undefined unless I define like this below
n2= int("%s%s" % (a,a))
print n2

Python Dictionary get()

dict.get(key[, value])

The get() method takes maximum of two parameters:

key - key to be searched in the dictionary

value (optional) - Value to be returned if the key is not found. The default value is None.

the value for the specified key if key is in dictionary.

None if the key is not found and value is not specified.

value if the key is not found and value is specified

The get() method returns the value for the specified key if key is in dictionary.

person = {'name': 'Phill', 'age': 22}

print('Name: ', person.get('name'))
print('Age: ', person.get('age'))

# value is not provided
print('Salary: ', person.get('salary'))

# value is provided
print('Salary: ', person.get('salary', 0.0))

Name:  Phill
Age:  22
Salary:  None
Salary:  0.0

Error_Handling

try and except

example:-

try:
    return 5/0
except ZeroDivisionError:
     print "Zero Division Error"

Lambda Function

evenNumbers = filter(lambda x: x%2==0, li
squaredNumbers = map(lambda x: x**2, range(1,21))```