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Python Functions Cheat Sheet by

Useful Python Built-in Functions

Math Module Functions

ceil(x)
Returns the smallest integer greater than or equal to x
copysi­gn(x, y)
Returns x with the sign of y
fabs(x)
Returns the absolute value of x
factor­ial(x)
Returns the factorial of x
floor(x)
Returns the largest integer less than or equal to x
fmod(x, y)
Returns the remainder when x is divided by y
isfini­te(x)
Returns True if x is neither an infinity nor a NaN (Not a Number)
isinf(x)
Returns True if x is a positive or negative infinity
isnan(x)
Returns True if x is a NaN
ldexp(x, i)
Returns x (2*i)
modf(x)
Returns the fractional and integer parts of x
exp(x)
Returns e**x
expm1(x)
Returns e**x – 1
log(x[, base])
Returns the logarithm of x to the base (defaults to e)
log2(x)
Returns the base-2 logarithm of x
log10(x)
Returns the base-10 logarithm of x
pow(x, y)
Returns x raised to the power y
sqrt(x)
Returns the square root of x
acos(x)
Returns the arc cosine of x
asin(x)
Returns the arc sine of x
atan(x)
Returns the arc tangent of x
atan2(y, x)
Returns atan(y / x)
cos(x)
Returns the cosine of x
hypot(x, y)
Returns the Euclidean norm, sqrt(xx + yy)
sin(x)
Returns the sine of x
tan(x)
Returns the tangent of x
degrees(x)
Converts angle x from radians to degrees
radians(x)
Converts angle x from degrees to radians
gamma(x)
Returns the Gamma function at x
lgamma(x)
Returns the natural logarithm of the absolute value of the Gamma function at x
pi
Mathem­atical constant, the ratio of circum­ference of a circle to it's diameter (3.141­59...)
e
mathem­atical constant e (2.718­28...)
* import math and use math.fun()

Sets Functions

S.add(e)
Adds the element e to the set S
S1.upd­ate(S2)
Adds the items specified in the set S2 to the set S1
S.remo­ve(e)
Remove the element e from the set S
S.pop()
Removes any element from the set S
S.clear()
Remove all element from the set S
S.copy()
Creates a copy of the set S
S1.uni­on(S2)
Returns a set containing elements from both S1 and S2
S1.int­ers­ect­ion(S2)
Returns a set containing elements common in set S1 and S2
S1.dif­fer­enc­e(S2)
Returns a set containing elements in set S1 but not in S2
S1.sym­met­ric­_di­ffe­ren­ce(S2)
Returns a set containing elements which are in one of the either sets S1 and S2, but not in both
 

String Functions

S.coun­t(str)
Counts the number of times string str occurs in string S
S.find­(str)
Returns index of first occurrence of string str in string S, and -1 if str is not present int string S
S.rfin­d(str)
Returns index of last occurrence of string str in string S, and -1 if str is not present in string S
S.capi­tal­ize()
Returns a string that has first letter of the string S in uppercase and rest of the characters in lowercase
S.title()
Returns a string that has first letter of every word in the string S in uppercase and rest of the characters in lowercase
S.lower()
Returns a string that has all uppercase characters in string S converted into lowercase characters
S.upper()
Returns a string that has all lower characters in string S converted into uppercase characters
S.swap­case()
Returns a string that has all lowercase characters in string S converted into uppercase characters and vice versa
S.isup­per()
Returns True if all alphabets in string S are in upperc­ase­,else False
S.islo­wer()
Returns True if all alphabets in string S are in lowerc­ase­,else False
S.isti­tle()
Returns True if string S is in titlecase
S.repl­ace­(st­r1,­str2)
Returns a string that has every occurrence of string str1 in S replaced by with the occurrence of string str2
S.strip()
Returns a string that has whites­paces in S removed from start and end
S.lstrip()
Returns a string that has whites­paces in S removed from start
S.rstrip()
Returns a string that has whites­paces in S removed from end
S.spli­t(d­eli­meter)
Returns a list formed by splitting the string S into various substring. The delimeter is used to mark the split points
S.part­iti­on(­del­imeter)
Partitions the string S into two parts base on delimeter and returns a tuple comprising of string before delimeter
S.join­(se­quence)
Returns a string comprising of elements of the sequence separated by delimeter S
S.issp­ace()
Returns True if all characters in string S comprise of whitespace characters only,i.e. ' ', '\n', '\t' else False
S.isal­pha()
Returns True if all characters in string S comprise of alphabets only, else False
S.isdi­git()
Returns True if all characters in string S comprise of digits only, else False
S.isal­num()
Returns True if all characters in string S comprise of alphabets and digits only, else False
S.star­tsw­ith­(str)
Returns True if string S starts with string str,else False
S.ends­wit­h(str)
Returns True if string S ends with string str,else False
S.enco­de(str)
Returns S in encoded format according to the given encoding scheme
S.deco­de(str)
Returns the decoded string S according to the given encoding scheme

List

L.appe­nd(e)
Adds the element e to the end of the list L
L.exte­nd(L2)
Adds the items specified in the list L2 at the end of the list L
L.remo­ve(e)
Remove the element e from the list L
L.pop(i)
Removes the element specified at index i from the list L*
L.count(e)
Returns count of occurrence of element e in list L
L.index(e)
Returns index of element e from list L
L.inse­rt(i,e)
Returns element e at the index i in list L
L.sort()
Sorts the elements of the list L
L.reve­rse()
Reverses the order elements in list L

File Handling

open(f­ile­nam­e,mode)
Open a file and store it as an object
file.c­lose()
Close a file which is opened
file.r­ead()
Read whole data from file
file.r­ead­line()
Read a line from file
file.r­ead­lines()
Read all the lines in a list from file
file.w­rit­e('­data')
Write data in a file
* Mode can be 'r', 'w' and 'a'
 

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