- 1. Day 1String, Control Flow, Data Structure Day 1
2. StringIntroductionString MethodsMulti-line StringString
FormatingUnicode StringIterating, Searching, Comparison Day 1 3.
String : IntroductionPython has a built-in string class named
"str"A "raw" string literal is prefixed by an rPython strings are
"immutable"Characters in a string can be accessed
using[index]Unlike Java, the + does not automatically
convertnumbers or other types to string form Day 1 4. String :
Methodss.lower(), s.upper()s.strip()s.isalpha(), s.isdigit(),
s.isspace()s.find(other)s.replace(old,
new)s.split(delim)s.join(list)s.center(width[, fillchar])Day 1 5.
String : Multi-LineDeclare StringUsing Single Quotes ()Using Double
Quotes (")Using Triple Quotes ( or """)raw = rthistn and thatmulti
= r"""It was the best of times.It was the worst of times."""Day 1
6. String : Formatingstr.format(*args, **kwargs)% operatortext =
("%d little pigs come out or Ill %s and %s and%s" % (3, huff, puff,
blow down))%(language)s has %(number)03d quote types. %{"language":
"Python", "number": 2}String = Whats your name? Day 1 7. String :
UnicodeDefine Unicode stringustring = uA unicode u018e string
xf1type(ustring) Unicode to UTF-8nstr =
ustring.encode(utf-8)type(nstr) UTF-8 to UnicodeDay 1 8. String :
Iterating, Searching, ComparisonLoop on stringfor s in str:Check
existence of stings in str ?Comparison of 2 strings===!=Day 1 9.
Control FlowCondition checkingLoopsForWhilebreak, continue, else
and pass statementRangeRange(10)Range(1, 10)Range(0, 10, 3) Day 1
10. Control Flow : Condition checking>>> x =
int(raw_input("Please enter an integer: "))Please enter an integer:
42>>> if x < 0:... x=0... print Negative changed to
zero... elif x == 0:... print Zero... elif x == 1:Day 1 11. Control
Flow : for loop>>> # Measure some strings:... a = [cat,
window, defenestrate]>>> for x in a:... print x,
len(x)...>>> for x in a[:]: # make a slice copy of the
entire listDay 1 12. Control Flow : break, continue and elseLoop
statements may have an else clause;it is executed when the loop
terminates through exhaustion of the list - (with for)when the
condition becomes false - (with while)not when the loop is
terminated by a break statementDay 1 13. Control Flow : for .
elsefor n in range(2, 10):... for x in range(2, n):... if n % x ==
0:... print n, equals, x, *, n/x... break... else:... # loop fell
through without finding a factor... print n, is a prime numberDay 1
14. Control Flow : passThe pass statement does nothingPass in
loops>>> while True:... pass # Busy-wait for keyboard
interrupt (Ctrl+C)Empty Class>>> class MyEmptyClass:...
pass... Day 1 15. Control Flow : passEmpty Method>>> def
initlog(*args):... pass # Remember to implement this!... Day 1 16.
Control Flow : range>>> range(5, 10)[5, 6, 7, 8,
9]>>> range(0, 10, 3)[0, 3, 6, 9]>>> range(-10,
-100, -30)[-10, -40, -70]>>> a = [Mary, had, a, little,
lamb]>>> for i in range(len(a)): ... print i, a[i] Day 1
17. Data StructurePython built-in typesTupleListDictUsageList
MethodsDict MethodsDict FormattingDay 1 18. Data Structure :
tupleTuples, like strings, are immutable:it is not possible to
assign to the individual items of a tuple>>> t = 12345,
54321, hello!>>> t[0]12345>>> t(12345, 54321,
hello!)Day 1 19. Data Structure : tuple reverse assignmentCreating
Tuple>>> t = 12345, 54321, hello!>>>
type(t)>>> t(12345, 54321, hello!)Reverse
Operation>>> x, y, z = tDay 1 20. Data Structure :
listPython has a great built-in list type named "list"lst = [],
Create a new listcolors = [red, blue, green]print colors[0] ##
redprint colors[2] ## greenprint len(colors) ## 3Assignment of
listb = colors ## Does not copy the list Day 1 21. Data Structure :
working with listL is t B u ild U plist = [] ## Start as the empty
listlist.append(a) ## Use append() to add elementslist.append(b)L
is t S lic e slist = [a, b, c, d]print list[1:-1] ## [b, c] Day 1
22. Data Structure : list methods>>> list = [larry, curly,
moe]>>> list.append(shemp) ## append elem at
end>>> list.insert(0, xxx) ## insert elem at index
0>>> list.extend([yyy, zzz]) ## add list of elems at
end>>> print list ## [xxx, larry, curly, moe, shemp, yyy,
zzz]Day 1 23. Data Structure : iterations over listUsing for
loopfor var in list>>> squares = [1, 4, 9, 16]>>>
sum = 0>>> for num in squares:>>> sum +=
num>>> print sum ## 30Day 1 24. Data Structure :
dictPythons efficient key/value hash table structure is called a
"dict"The contents of a dict can be written as a series of
key:value pairse.g. dict = {key1:value1, key2:value2, ... }The
"empty dict" is just an empty pair of curly braces {}Looking up or
setting a value in a dict uses square brackets. e.g. dict[foo]Day 1
25. Data Structure : creating dict## Can build up a dict by
starting with the the empty dict {}## and storing key/value pairs
into the dict like this:## dict[key] = value-for-that-keydict =
{}dict[a] = alphadict[g] = gammadict[o] = omega Day 1 26. Data
Structure : Iteration on key or value## By default, iterating over
a dict iterates over its keys.## Note that the keys are in a random
order.for key in dict: print key## prints a g o## Exactly the same
as abovefor key in dict.keys(): print key Day 1 27. Data Structure:
Iteration on key and value## This loop syntax accesses the whole
dict by looping## over the .items() tuple list, accessing one (key,
value)## pair on each iteration.for k, v in dict.items():print k,
>, v## a > alphao > omega g > gamma Day 1 28. Data
Structure : del an itemvar = 6del var # var no more!list = [a, b,
c, d]del list[0]## Delete first elementdel list[-2:] ## Delete last
two elementsprint list## [b]Day 1 29. Data Structure : sortingThe
easiest way to sort is with the sorted(list) functionThe sorted()
function seems easier to use compared to sort()The sorted()
function can be customized though optional argumentsThe sorted()
optional argument reverse=TrueCustom Sorting With key= Day 1 30.
Data Structure : working with sorted( )S o r t in g N u m b e r sa
= [5, 1, 4, 3]print sorted(a) ## [1, 3, 4, 5]print a ## [5, 1, 4,
3]S o r t in g S t r in gstrs = [aa, BB, zz, CC]print sorted(strs)
## [BB, CC, aa, zz] (casesensitive) Day 1 31. Data Structure :
Custom Sorting with keystrs = [ccc, aaaa, d, bb]print sorted(strs,
key=len) ## [d, bb, ccc,aaaa]Day 1 32. Data Structure : Custom
comparator## Say we have a list of strings we want to sort by
thelast letter of the string.strs = [xc, zb, yd ,wa]## Write a
little function that takes a string, and returnsits last letter.##
This will be the key function (takes in 1 value, returns1
value).def MyComparator(s):Day 1 33. Next Session ?FunctionDynamic
FunctionsObject OrientedClassInheritanceMethod Overload,
OverridePython Packaging__init__.pyDay 1 34. Contact me... Mantavya
Gajjar Phone : 94263 40093Email : [email protected] Website :
www.opentechnologies.inFollow on Twitter : @mantavyagajjarDay 1
