Basics of Python and Numpy_583aab2b47e30ad9647bc4aaf13b884d.pdf

An introductory peresentation which teaches about Python commands and Numpy

1. Basics of Python
and
Numpy

2. Introduction
➢Pythonisaninterpreted,interactive,object-
oriented,andhigh-levelprogramminglanguage.
➢PythonFeatures
➢Easy-to-learn
➢Easy-to-read
➢Abroadstandardlibrary
➢Databases
➢GUIProgramming

3. Introduction
➢PythonComments:#
➢HelpinPython:help(topic)
➢Ifnoargumentisgiven,theinteractivehelpsystem
startsontheinterpreterconsole.Iftheargumentisa
string,thenthestringislookedupasthenameofa
module,function,class,method,keyword,or
documentationtopic,andahelppageisprintedonthe
console.

4. Printing in Python
➢Syntax:print(value,...,sep='',end='\n',file=sys.stdout,flush=False)
➢print("HelloWorld")#HelloWorld
➢a=5
➢b=2
➢print(a) #5
➢print(a,b) #52
➢print(a) #5
print(b) #2
➢print(“Valueofa=“,a)
➢print(“Valueofb=“,b)

5. Standard Data Types
➢Pythonhasfivestandarddatatypes−
➢Numbers
➢String
➢List
➢Tuple
➢Dictionary

6. Standard Data Types
➢Numbers
➢int
➢AllintegersinPython3arerepresentedaslongintegers.Hence
thereisnoseparatenumbertypeaslong.
➢IntegersinPython3areofunlimitedsize.
➢float
➢complex
➢Acomplexnumberconsistsofanorderedpairofrealfloating-
pointnumbersdenotedbyx+yj,wherexandyarethereal
numbersandjistheimaginaryunit.

7. Standard Data Types
➢Numbers
➢Examples
int float complex
10 0.0 3.14j
100 15.20 45.j
-786 -21.9 9.322e1-36j
0o70 32.3e18 .876j
-0o470 -90. -.6545+0J
-0x260 -32.54e100 3e1+26J
0x69 70.2E-12 4.53e1-7j

8. Standard Data Types
➢Strings
➢StringsinPythonareidentifiedasacontiguoussetof
charactersrepresentedinthequotationmarks.
➢Pythonallowsforeitherpairsofsingleordoublequotes.
➢Subsetsofstringscanbetakenusingthesliceoperator
([]and[:])withindexesstartingat0inthebeginningof
thestring.
➢Theplus(+)signisthestringconcatenationoperatorand
theasterisk(*)istherepetitionoperator.
➢Tryingtoaccesselementsbeyondthelengthofthe
stringresultsinanerror.

9. Standard Data Types
➢Strings
➢str='HelloWorld!'
➢print(str) #Printscompletestring
➢print(str[0]) #Printsfirstcharacterofthestring
➢print(str[2:5]) #Printscharactersstartingfrom3rdto5th
➢print(str[2:]) #Printsstringstartingfrom3rdcharacter
➢print(str*2) #Printsstringtwotimes
➢print(str+"TEST")#Printsconcatenatedstring
➢Thiswillproducethefollowingresult−
➢HelloWorld!
➢H
➢llo
➢lloWorld!
➢HelloWorld!HelloWorld!
➢HelloWorld!TEST

10. Standard Data Types
➢Strings
➢str='HelloWorld!'
➢print(str[-1])
➢print(str[-3:-1])
➢print(str[-12:])
➢Thiswillproducethefollowingresult−
➢!
➢ld
➢HelloWorld!

11. Standard Data Types
➢Strings
➢Pythonstringscannotbechanged—theyareimmutable.
➢Therefore,assigningtoanindexedpositioninthestring
resultsinanerror
➢I.e.str[0]=‘J’resultsinanerror.However,str=“welcome”works.

12. Standard Data Types
➢List
➢Alistcontainsitemsseparatedbycommasandenclosedwithin
squarebrackets([]).
➢Tosomeextent,listsaresimilartoarraysinC.One
differencebetweenthemisthatalltheitemsbelongingtoa
listcanbeofdifferentdatatype.
➢Thevaluesstoredinalistcanbeaccessedusingtheslice
operator([]and[:])withindexesstartingat0inthe
beginningofthelistandworkingtheirwayfrom-1attheend.
➢Theplus(+)signisthelistconcatenationoperator,andthe
asterisk(*)istherepetitionoperator.
➢Unlikestrings,whichareimmutable,listsareamutabletype,
i.e.itispossibletochangetheircontent.
➢Tryingtoaccess/assignelementsbeyondthelengthofthelist
resultsinanerror.

13. Standard Data Types
➢List
➢list=['abcd',786,2.23,'john',70.2]
➢tinylist=[123,'john']
➢print(list) #Printscompletelist
➢print(list[0])#Printsfirstelementofthelist
➢print(list[1:3])#Printselementsstartingfrom2ndtill3rd
➢print(list[2:])#Printselementsstartingfrom3rdelement
➢print(tinylist*2)#Printslisttwotimes
➢print(list+tinylist)#Printsconcatenatedlists
➢Thisproducethefollowingresult−
➢['abcd',786,2.23,'john',70.2]
➢abcd
➢[786,2.23]
➢[2.23,'john',70.2]
➢[123,'john',123,'john']
➢['abcd',786,2.23,'john',70.2,123,'john']

14. Standard Data Types
➢Tuples
➢Atupleisanothersequencedatatypethatissimilartothe
list.
➢Atupleconsistsofanumberofvaluesseparatedbycommas.
➢Unlikelists,however,tuplesareenclosedwithinparentheses.
➢Themaindifferencesbetweenlistsandtuplesare:Listsare
enclosedinbrackets([])andtheirelementsandsizecanbe
changed,whiletuplesareenclosedinparentheses(())and
cannotbeupdated.
➢Tuplescanbethoughtofasread-onlylists/immutablelists.

15. Standard Data Types
➢Tuples
➢tuple=('abcd',786,2.23,'john',70.2)
➢tinytuple=(123,'john')
➢print(tuple) #Printscompletetuple
➢print(tuple[0]) #Printsfirstelementofthetuple
➢print(tuple[1:3]) #Printselementsstartingfrom2ndtill3rd
➢print(tuple[2:]) #Printselementsstartingfrom3rdelement
➢print(tinytuple*2)#Printstupletwotimes
➢print(tuple+tinytuple)#Printsconcatenatedtuple
➢Thisproducethefollowingresult−
➢('abcd',786,2.23,'john',70.2)
➢abcd
➢(786,2.23)
➢(2.23,'john',70.2)
➢(123,'john',123,'john')
➢('abcd',786,2.23,'john',70.2,123,'john')

16. Standard Data Types
➢Tuples
➢tuple=('abcd',786,2.23,'john',70.2)
➢list=['abcd',786,2.23,'john',70.2]
➢tuple[2]=1000#Invalidsyntaxwithtuple
➢list[2]=1000#Validsyntaxwithlist

17. Standard Data Types
➢Dictionary
➢Dictionariesconsistofkey-valuepairs.
➢AdictionarykeycanbealmostanyPythontype,butareusually
numbersorstrings.
➢Values,ontheotherhand,canbeanyarbitraryPythonobject.
➢Dictionariesareenclosedbycurlybraces({})andvaluescan
beassignedandaccessedusingsquarebraces([]).
➢Dictionarieshavenoconceptoforderamongelements.
➢Itisincorrecttosaythattheelementsare"outoforder";
theyaresimplyunordered.
➢Dictionariesaremutable.

18. Standard Data Types
➢Dictionary
➢dict={}
➢dict['one']="Thisisone"
➢dict[2]="Thisistwo"
➢tinydict={'name':'john','code':6734,'dept':'sales'}
➢print(dict['one'])#Printsvaluefor'one'key
➢print(dict[2]) #Printsvaluefor2key
➢print(tinydict) #Printscompletedictionary
➢print(tinydict.keys())#Printsallthekeys
➢print(tinydict.values())#Printsallthevalues
➢Thisproducethefollowingresult−
➢Thisisone
➢Thisistwo
➢{'dept':'sales','code':6734,'name':'john'}
➢['dept','code','name']
➢['sales',6734,'john']

19. Input Statement
➢a=input(“Entera:”)
➢a=int(input(“Entera:”));
➢a=eval(input("Enterthreevalues:"))
➢a,b,c=eval(input(“Entera,b,c:”))

20. Matrices
➢a=[
[1,2,3],
[4,5,6]
]
➢a[0],a[1],a[0][0],a[0][2],a[1][2]
Note: Not Recommended as the lenwill be 2.

21. Basic Operators
➢TypesofOperator
➢ArithmeticOperators
➢Comparison(Relational)Operators
➢AssignmentOperators
➢LogicalOperators
➢BitwiseOperators
➢MembershipOperators
➢IdentityOperators

22. Basic Operators
➢ArithmeticOperators
➢Assumevariableaholds10andvariablebholds21,then−
Operator Description Example
+ Addition Adds values on either side of the operator.a + b = 31
-SubtractionSubtracts right hand operand from left hand
operand.
a –b = -11
* MultiplicationMultiplies values on either side of the
operator
a * b = 210
/ Division Divides left hand operand by right hand
operand
b / a = 2.1
% Modulus Divides left hand operand by right hand
operand and returns remainder
b % a = 1
** Exponent Performs exponential (power) calculation on
operators
a**b =10 to
the power 21
// Floor Division -The division of operands
where the result is the quotient in which the
digits after the decimal point are removed.
But if one of the operands is negative, the
result is floored, i.e., rounded away from
zero (towards negative infinity):
9//2 = 4 and
9.0//2.0 = 4.0

23. Basic Operators
➢ComparisonOperators
➢Assumevariableaholds10andvariablebholds20,then-
Operator Description Example
== If the values of two operands are equal,
then the condition becomes true.
(a == b) is not true.
!= If values of two operands are not equal,
then condition becomes true.
(a!= b) is true.
> If the value of left operand is greater
than the value of right operand, then
condition becomes true.
(a > b) is not true.
< If the value of left operand is less than
the value of right operand, then condition
becomes true.
(a < b) is true.
>= If the value of left operand is greater
than or equal to the value of right
operand, then condition becomes true.
(a >= b) is not true.
<= If the value of left operand is less than or
equal to the value of right operand, then
condition becomes true.
(a <= b) is true.

24. Basic Operators
➢AssignmentOperators
➢Assumevariableaholds10andvariablebholds20,then-
Operator Description Example
= Assigns values from right side operands to
left side operand
c = a + b assigns value
of a + b into c
+= It adds right operand to the left operand and
assign the result to left operand
c += a is equivalent to
c = c + a
-= It subtracts right operand from the left
operand and assign the result to left operand
c -= a is equivalent to
c = c -a
*= It multiplies right operand with the left
operand and assign the result to left operand
c *= a is equivalent to
c = c * a
/= It divides left operand with the right operand
and assign the result to left operand
c /= a is equivalent to
c = c / a
%= It takes modulus using two operands and
assign the result to left operand
c %= a is equivalent to
c = c % a
**= Performs exponential (power) calculation on
operators and assign value to the left operand
c **= a is equivalent
to c = c ** a
//= It performs floor division on operators and
assign value to the left operand
c //= a is equivalent
to c = c // a

25. Basic Operators
➢BitwiseOperators
➢Assumea=60=00111100andb=13=00001101,then-
Operator Description Example
& Operator copies a bit to the result
if it exists in both operands
(a & b) (means 0000 1100)
| It copies a bit if it exists in either
operand.
(a | b) = 61 (means 0011
1101)
^ It copies the bit if it is set in one
operand but not both.
(a ^ b) = 49 (means 0011
0001)
~ It is unary and has the effect of
'flipping' bits.
(~a ) = -61 (means 1100
0011 in 2's complement
form due to a signed
binary number.
<< The left operands value is moved
left by the number of bits
specified by the right operand.
a << = 2 (means 1111
0000)
>> The left operands value is moved
right by the number of bits
specified by the right operand.
a >> = 2 (means 0000
1111)

26. Basic Operators
➢LogicalOperators
➢Assumea=True(CaseSensitive)andb=False(Case
Sensitive),then-
Operator Description Example
and If both the operands are true
then condition becomes true.
(a and b) is False.
or If any of the two operands
are non-zero then condition
becomes true.
(a or b) is True.
not Used to reverse the logical
state of its operand.
Not(a and b) is True.

27. Basic Operators
➢MembershipOperators
➢Python’smembershipoperatorstestformembershipina
sequence,suchasstrings,lists,ortuples.
➢Therearetwomembershipoperatorsasexplainedbelow
Operator Description Example
in Evaluates to true if it finds a
variable in the specified
sequence and false otherwise.
x in y, here “in” results in a
1 if x is a member of
sequence y.
not inEvaluates to true if it does not
finds a variable in the specified
sequence and false otherwise.
x not in y, here “not in”
results in a 1 if x is not a
member of sequence y.

28. Basic Operators
➢IdentityOperators
➢Identityoperatorscomparethememorylocationsoftwo
objects.
➢TherearetwoIdentityoperatorsexplainedbelow:
Operator Description Example
is Evaluates to true if the
variables on either side of the
operator point to the same
object and false otherwise.
x is y, here”is”results in 1
if id(x) equals id(y).
is not Evaluates to false if the
variables on either side of the
operator point to the same
object and true otherwise.
x is not y, here”is
not”results in 1 if id(x) is
not equal to id(y).

29. Basic Operators
➢PythonOperatorPrecedence
➢
Operator Description
** Exponentiation (raise to the power)
~ + - Complement, unary plus and minus
* / % // Multiply, divide, modulo and floor division
+ - Addition and subtraction
>> << Right and left bitwise shift
& Bitwise 'AND'
^ | Bitwise exclusive `OR' and regular `OR'
<= < > >= Comparison operators
<> == != Equality operators
= %= /= //= -= += *=
**=
Assignment operators
is is not Identity operators
in not in Membership operators
not or and Logical operators

30. Decision Making
➢Simpleif
➢ifexpression:
statement(s)
var1=100
ifvar1:
print("1-Gotatrueexpressionvalue")
print(var1)
var2=0
ifvar2:
print("2-Gotatrueexpressionvalue")
print(var2)
print("Goodbye!")
Output:
1-Gotatrueexpressionvalue
100
Goodbye!

31. Decision Making
➢ifelse
➢ifexpression:
statement(s)
else:
statement(s)
amount=int(input(“Enteramount:“))
ifamount<1000:
discount=amount*0.05
print("Discount",discount)
else:
discount=amount*0.10
print("Discount",discount)
print("Netpayable:",amount-discount)

32. Decision Making
➢ifelse
Output:
Enteramount:600
Discount30.0
Netpayable:570.0
Enteramount:1200
Discount120.0
Netpayable:1080.0

33. Decision Making
➢elifStatement
ifexpression1:
statement(s)
elifexpression2:
statement(s)
elifexpression3:
statement(s)
else:
statement(s)

34. Decision Making
➢elifStatement
amount=int(input("Enteramount:"))
ifamount<1000:
discount=amount*0.05
print("Discount",discount)
elifamount<5000:
discount=amount*0.10
print("Discount",discount)
else:
discount=amount*0.15
print("Discount",discount)
print("Netpayable:",amount-discount)

35. Decision Making
➢elifStatement
Enteramount:600
Discount30.0
Netpayable:570.0
Enteramount:3000
Discount300.0
Netpayable:2700.0
Enteramount:6000
Discount900.0
Netpayable:5100.0

36. Decision Making
➢Nestedif
ifexpression1:
statement(s)
ifexpression2:
statement(s)
elifexpression3:
statement(s)
else:
statement(s)
elifexpression4:
statement(s)
else:
statement(s)

37. Decision Making
➢Nestedif
num=int(input("enternumber"))
ifnum%2==0:
ifnum%3==0:
print("Divisibleby3and2")
else:
print("divisibleby2notdivisibleby3")
else:
ifnum%3==0:
print("divisibleby3notdivisibleby2")
else:
print("notDivisibleby2notdivisibleby3")

38. Loops
➢WhileLoop
whileexpression:
statement(s)
count=0
whilecount<9:
print('Thecountis:',count)
count=count+1
print("Goodbye!")

39. Loops
➢WhileLoop
Thecountis:0
Thecountis:1
Thecountis:2
Thecountis:3
Thecountis:4
Thecountis:5
Thecountis:6
Thecountis:7
Thecountis:8
Goodbye!

40. Loops
➢forLoop
foriterating_varinsequence:
statements(s)
forvarinlist(range(5)):
print(var)
Output:
0
1
2
3
4

41. Loops
➢forLoop
forletterin'Python':#traversalofastringsequence
print('CurrentLetter:',letter)
Output:
CurrentLetter:P
CurrentLetter:y
CurrentLetter:t
CurrentLetter:h
CurrentLetter:o
CurrentLetter:n

42. Loops
➢forLoop
fruits=['banana','apple','mango']
forfruitinfruits: #traversalofListsequence
print('Currentfruit:',fruit)
print("Goodbye!")
Output:
Currentfruit:banana
Currentfruit:apple
Currentfruit:mango
Goodbye!

43. Loops
➢forLoop
➢IteratingbySequenceIndex
fruits=['banana','apple','mango']
forindexinrange(len(fruits)):
print('Currentfruit:',fruits[index])
print("Goodbye!")
Output:
Currentfruit:banana
Currentfruit:apple
Currentfruit:mango
Goodbye!

44. Loops
➢BreakStatement
forletterin'Python':
ifletter=='h':
break
print('CurrentLetter:',letter)
Output:
CurrentLetter:P
CurrentLetter:y
CurrentLetter:t

45. Loops
➢ContinueStatement
forletterin'Python':
ifletter=='h':
continue
print('CurrentLetter:',letter)
Output:
CurrentLetter:P
CurrentLetter:y
CurrentLetter:t
CurrentLetter:o
CurrentLetter:n

46. Loops
➢UsingelseStatementwithLoops
•Pythonsupportstohaveanelsestatementassociatedwith
aloopstatement
•Iftheelsestatementisusedwithaforloop,theelse
blockisexecutedonlyifforloopsterminatesnormally
(andnotbyencounteringbreakstatement).
•Iftheelsestatementisusedwithawhileloop,theelse
statementisexecutedwhentheconditionbecomesfalse.

47. Loops
➢UsingelseStatementwithLoops
numbers=[11,33,55,39,55,75,37,21,23,41,13]
fornuminnumbers:
ifnum%2==0:
print('thelistcontainsanevennumber')
break
else:
print('thelistdoesnotcontainevennumber')
Output:
thelistdoesnotcontainevennumber

48. Numbers -Revisited
➢Numbers
➢NumberTypeConversion
➢Typeint(x)toconvertxtoaplaininteger.
➢Typefloat(x)toconvertxtoafloating-pointnumber.
➢Typecomplex(x)toconvertxtoacomplexnumberwithrealpart
xandimaginarypartzero.
➢Typecomplex(x,y)toconvertxandytoacomplexnumberwith
realpartxandimaginaryparty.xandyarenumericexpressions.

49. Numbers -Revisited
➢Numbers
➢MathematicalFunctions
Function Returns ( description )
abs(x) The absolute value of x: the (positive)
distance between x and zero.
math.ceil(x)The ceiling of x: the smallest integer not
less than x
math.exp(x) The exponential of x: e
x
math.floor(x)The floor of x: the largest integer not
greater than x
math.log(x) The natural logarithm of x, for x> 0
math.log10(x) The base-10 logarithm of x for x> 0 .

50. Numbers -Revisited
➢Numbers
➢MathematicalFunctions
Function Returns ( description )
max(x1, x2,...)The largest of its arguments: the value
closest to positive infinity
min(x1, x2,...)The smallest of its arguments: the value
closest to negative infinity
pow(x, y) The value of x**y.
round(x [,n])xrounded to n digits from the decimal
point.
math.sqrt(x) The square root of x for x > 0

51. Strings -Revisited
➢Strings(Assumestrtobeastringvariable)
Sr.
No.
Methods with Description
1 str.capitalize()
Capitalizes first letter of string. Not in Place
2 str.isalnum()
Returns true if string has at least 1 character and all
characters are alphanumeric and false otherwise.
3 str.isalpha()
Returns true if string has at least 1 character and all
characters are alphabetic and false otherwise.
4 str.isdigit()
Returns true if string has at least 1 character and contains
only digits and false otherwise.
5 str.islower()
Returns true if string has at least 1 cased character and all
cased characters are in lowercase and false otherwise.
6 str.isspace()
Returns true if string contains only whitespace characters and
false otherwise.

52. Strings -Revisited
➢Strings
Sr.
No.
Methods with Description
7 str.isupper()
Returns true if string has at least one cased character and all
cased characters are in uppercase and false otherwise.
8 len(str)
Returns the length of the string
9 str.lower()
Converts all uppercase letters in string to lowercase. Not in
Place.
10 max(str)
Returns the max alphabetical character from the string str.
11 min(str)
Returns the min alphabetical character from the string str.
12 str.upper()
Converts lowercase letters in string to uppercase. Not in Place.

53. Lists -Revisited
➢DeleteListElements
list=['physics','chemistry',1997,2000]
print(list)
dellist[2]
print("Afterdeletingvalueatindex2:",list)
Output:
['physics','chemistry',1997,2000]
Afterdeletingvalueatindex2:['physics',
'chemistry',2000]

54. Lists -Revisited
➢BasicListOperations
Python Expression Results Description
len([1, 2, 3]) 3 Length
[1, 2, 3] + [4, 5, 6] [1, 2, 3, 4, 5, 6] Concatenation
['Hi!'] * 4 ['Hi!', 'Hi!', 'Hi!', 'Hi!']Repetition
3 in [1, 2, 3] True Membership
for x in [1,2,3] : print
(x,end=' ')
1 2 3 Iteration

55. Lists -Revisited
➢BuiltinListFunctionsandMethods(assumelistto
benameofthevariable)
Sr. Function with Description
1 len(list)
Gives the total length of the list.
2 max(list)
Returns item from the list with max value.
3 min(list)
Returns item from the list with min value.
4 list.copy()
Returns a copy of the list

56. Lists -Revisited
➢ListMethods
SN Methods with Description
1 list.append(obj)
Appends object objto list. Returns None.
2 list.count(obj)
Returns count of how many times objoccurs in list
3 list.index(obj)
Returns the lowest index in list that objappears
4 list.insert(index, obj)
Inserts object objinto list at offset index
5 list.pop()
Removes and returns last object or objfrom list
6 list.remove(obj)
Removes first instance of objfrom list
7 list.reverse()
Reverses objects of list in place
8 list.sort()
Sorts objects of list in place

57. Python Functions
➢DefiningaFunction
deffunctionname(parameters):
"function_docstring"
function_suite
return[expression]
defprintme(str):
"Thisprintsapassedstringintothisfunction"
print(str)
return

58. Python Functions
➢Passbyreferencevsvalue
➢Allparameters(arguments)inthePythonlanguageare
passedbyreference.
➢Itmeansifyouchangewhataparameterreferstowithin
afunction,thechangealsoreflectsbackinthecalling
function.

59. Python Functions
➢Passbyreferencevsvalue
#Functiondefinitionishere
defchangeme(mylist):
"Thischangesapassedlistintothisfunction"
print("Valuesinsidethefunctionbeforechange:",mylist)
mylist[2]=50
print("Valuesinsidethefunctionafterchange:",mylist)
return
#Nowyoucancallchangemefunction
mylist=[10,20,30]
changeme(mylist)
print("Valuesoutsidethefunction:",mylist)
Output:
Valuesinsidethefunctionbeforechange:[10,20,30]
Valuesinsidethefunctionafterchange:[10,20,50]
Valuesoutsidethefunction:[10,20,50]

60. Python Functions
➢Passbyreferencevsvalue
#Functiondefinitionishere
defchangeme(mylist):
"Thischangesapassedlistintothisfunction"
mylist=[1,2,3,4] #Thiswouldassignnewreferenceinmylist
print("Valuesinsidethefunction:",mylist)
return
#Nowyoucancallchangemefunction
mylist=[10,20,30]
changeme(mylist)
print("Valuesoutsidethefunction:",mylist)
Output:
Valuesinsidethefunction:[1,2,3,4]
Valuesoutsidethefunction:[10,20,30]

61. Python Functions
➢Globalvs.LocalVariables
➢Variablesthataredefinedinsideafunctionbodyhavea
localscope,andthosedefinedoutsidehaveaglobal
scope.
➢Thismeansthatlocalvariablescanbeaccessedonly
insidethefunctioninwhichtheyaredeclared,whereas
globalvariablescanbeaccessedthroughouttheprogram
bodybyallfunctions.

62. Python Functions
➢Globalvs.LocalVariables
total=0#Thisisaglobalvariable.
#Functiondefinitionishere
defsum(arg1,arg2):
#Addboththeparametersandreturnthem."
total=arg1+arg2;#Heretotalislocalvariable.
print("Insidethefunctionlocaltotal:",total)
return
#Nowyoucancallsumfunction
sum(10,20)
print("Outsidethefunctionglobaltotal:",total)
Output:
Insidethefunctionlocaltotal:30
Outsidethefunctionglobaltotal:0

63. Python Functions
➢Globalvs.LocalVariables
total=0#Thisisglobalvariable.
#Functiondefinitionishere
defsum(arg1,arg2):
#Addboththeparametersandreturnthem."
globaltotal
total=arg1+arg2;
print("Insidethefunctionlocaltotal:",total)
return
#Nowyoucancallsumfunction
sum(10,20)
print("Outsidethefunctionglobaltotal:",total)
Output:
Insidethefunctionlocaltotal:30
Outsidethefunctionglobaltotal:30
Note:Youcanalsoreturnmultiplevalues,e.g.returnx,y

64. Miscellaneous
➢delvar_name
➢delvar1,var2
➢type(5)
➢type(5.6)
➢type(5+2j)
➢type(“hello”)
➢type([‘h’,’e’])
➢type((‘h’,’e’))
➢MultipleAssignments
➢a=b=c=1
➢a,b,c=1,2,"john"

65. Numpy
➢Numpy(Numeric/NumericalPython)
➢Numpyisanopen-sourceadd-onmodulethatprovides
commonmathematicalandnumericalroutinesaspre-
compiledfastfunctions
➢Itprovidesbasicroutinesformanipulatinglargearrays
andmatricesofnumericdata.
➢importnumpyasnp
➢C:\\Python34\scripts>pip3.4list
➢C:\\Python34\scripts>pip3.4installnumpy

66. Numpy
➢np.array
➢Collectionofsametypeofelements
➢Onedimensionalarray

67. Numpy
➢np.array
➢Twodimensionalarray

68. Numpy
➢np.array
➢Twodimensionalarray:reshape()&copy()
Strange -Shape is a settable property and it is a tuple and you can concatenate the dimension.

69. Numpy
➢np.array
➢Twodimensionalarray:reshape(),transpose()&flatten()

70. Numpy
➢np.array
➢Twodimensionalarray:concatenate()

71. Numpy
➢np.array
➢Twodimensionalarray:concatenate()

72. Numpy
➢np.array
➢Otherwaystocreatearray

73. Numpy
➢np.array
➢Arraymathematics

74. Numpy
➢np.array
➢Arraymathematics

75. Numpy
➢np.array
➢Arraymathematics-Broadcasting

76. Numpy
➢np.array
➢Arraymathematics-Broadcasting

77. Numpy
➢np.array
➢Arraymathematics

78. Numpy
➢np.array
➢Arraymathematics

79. Numpy
➢np.array
➢Arrayiteration

80. Numpy
➢np.array
➢Basicarrayoperations
➢np.mean(a)
➢np.var(a)
➢np.std(a)
➢np.min(a)
➢np.max(a)
➢np.argmin(a)
➢np.argmax(a)
➢np.sort(a)(notinplace)

81. Numpy
➢np.array
➢Basicarrayoperations
➢a=np.array([[1,2],[3,4]]) [
[1,2],
[3,4]
]
➢np.mean(a) #2.5
➢np.mean(a,axis=0)#array([2.,3.])#columnwise
➢np.mean(a,axis=1)#array([1.5,3.5])#rowwise
➢b=np.array([[11,5,14],[2,5,1]])[
[11,5,14],
[2,5,1]
]
➢np.sort(b) #array([[5,11,14],
[1,2,5]])
➢np.sort(b,axis=1) #array([[5,11,14],
[1,2,5]])
➢np.sort(b,axis=0) #array([[2,5,1],
[11,5,14]])

82. Numpy
➢np.array
➢Basicarrayoperations

83. Numpy
➢np.array
➢ComparisonOperators&ValueTesting

84. Numpy
➢np.array
➢ComparisonOperators&ValueTesting

85. Numpy
➢np.array
➢WhereFunction

86. Numpy
➢np.array
➢CheckingforNaNandInf

87. Numpy
➢np.array
➢ArrayItemSelection&Manipulation

88. Numpy
➢np.array
➢VectorandMatrixMathematics

89. Numpy
➢np.array
➢VectorandMatrixMathematics

90. Numpy
➢np.array
➢Statistics

91. Numpy
➢np.array
➢RandomNumbers

92. Numpy
➢np.array
➢RandomNumbers

93. Saving and Loading NumpyArray
#Singlearraysavingandloading
x=np.arange(10)
#save
np.save(‘outfile’,x)
#load
x=np.load(‘outfile.npy’)
print(x)

94. Saving and Loading NumpyArray
#Multiplearraysavingandloading
x=np.arange(10)
y=np.random.randint(1,10,(2,3))
#save
np.savez(‘outfile’,x,y)#ornp.savez(‘outfile’,x=x,y=y)
#load
dict=np.load(‘outfile.npz’)
x=dict[‘arr_0’] #orx=dict[‘x’]
y=dict[‘arr_1’] #ory=dict[‘y’]
print(x,y)

95. Disclaimer
➢Contentofthispresentationisnotoriginalandit
hasbeenpreparedfromvarioussourcesfor
teachingpurpose.