Python Cheat Sheet 2.7

Basic Python Functions and Methods (v. 2.7.10) 
Basic Built-in Functions 

raw_input()  

Reads a line from input, converts it to a string and returns that  

len()  

Returns the length (the number of items) of an object  

max()  

Returns the largest item in the list or the largest of the two or more arguments  

min()  

Returns the smallest item in the list or the smallest of the two or more arguments  

pow()  

Returns first argument to the power second argument  

range(start, stop, step)  

Returns a list of integers starting from start and ending at stop (exclusive), having a difference of step between any two adjacent elements  

xrange()  

Similar to range(), but returns an xrange iterator object instead of a list  

bin()  

Converts an integer number to a binary string  

oct()  

Converts an integer number to an octal string  

hex()  

Converts an integer nuber to a lowercase hexadecimal string prefixed with ‘0x’  

int()  

Returns an integer object from a number or string  

float()  

Returns a floating point number from a number or string  

type()  

Returns the type of any object  

File Methods and Constants 

open()  Opens a file, returning an object of the file type  
close()  Closes the file; a closed file cannot be read or written any more  
flush()  Flushes the internal buffer  
fileno()  Returns the integer “file descriptor” that is used by the underlying implementation to request I/O operations from the operating system  
tell()  Returns the file’s current position  
truncate()  Truncates the file’s size  
write()  Writes a string to the file  
writelines()  Writes a sequence of strings to the file  
closed  Bool indicating the current state of the file object  
encoding  The encoding that this file uses  
errors  The Unicode error handler used along with the encoding  
mode  The I/O mode for the file  
name  The name of the file  

String Methods 

str()  

Create a new empty string  

upper()  

Returns a string in all uppercase  

lower()  

Returns a string in all lowercase  

capitalize()  

Returns a string with first character capitalized, the rest lower  

strip()  

Returns a string with the leading and trailing whitespace removed  

lstrip()  

Returns a string with the leading whitespace removed  

rstrip()  

Returns a string with the trailing whitespace removed  

count()  

Returns the number of occurrences of item  

replace()  

Replaces all occurrences of old substring with new  

center()  

Returns a string centered in a field of width spaces  

ljust()  

Returns a string left justified in a field of width spaces  

rjust()  

Returns a string right justified in a field of width spaces  

find()  

Returns the leftmost index where the substring item is found  

rfind()  

Returns the rightmost index where the substring item is found  

index()  

Similar to find() except causes a runtime error if item is not found  

rindex()  

Similar to rfind() except causes a runtime error if item is not found  

chr()  

Returns a string of one character whose ASCII code is the integer passed as argument  

ord()  

Returns an integer representing the Unicode code point of any string of one character  

Math Functions and Constants 

abs() Returns the absolute value of a number factorial() Returns factorial of the argument value round() Returns the floating point value number to the given number of digits after the decimal point exp() Returns the argument raised to a power (e**x) log() Returns logarithm of argument value pow() Returns first parameter raised to the power by second parameter sqrt() Takes squareroot of argument value pi The mathematical constant π = 3.141592… e The mathematical constant e = 2.718281  

List (Array) Methods 

list()  Creates a new empty list  
append()  Adds an item to the end of the list  
extend()  Extends the list by appending all the items in the given list  
insert()  Inserts an item at a given position  
remove()  Removes the first item from the list with aforementioned parameter value  
pop()  Removes the item at the given position in the list, and return it  
index()  Returns the index in the list  
count()  Returns the number of times that appears in the list.  
sort()  Sorts the items of the list in place  
sort(reverse=True)  Sorts the items of the list in place, in descending order  
reverse()  Reverses the elements of the list, in place  
sum()  Returns the total sum of all items of the list  
join()  Concatenates all the items of the list  

Dictionary Methods 

dict()  Creates a new empty dictionary  
keys()  Returns list of dictionary keys  
values()  Returns list of dictionary values  
clear()  Removes all elements of dictionary  
copy()  Returns a shallow copy of dictionary  

Date and Time Methods 

replace()  Gives new values by whichever keyword arguments are specified  
toordinal()  Returns the proleptic Gregorian ordinal of the date, where January 1 of year 1 has ordinal 1  
weekday()  Returns the day of the week as an integer, where Monday is 0 and Sunday is 6  
isoweekday()  Returns the day of the week as an integer, where Monday is 1 and Sunday is 7  
isocalendar()  Returns a 3-tuple, (ISO year, ISO week number, ISO weekday)  
isoformat()  Returns a string representing the date in ISO 8601 format, “YYYY-MM-DD”  
__str__()  For a date d, str(d) is equivalent to d.isoformat()  
ctime()  Returns a string representing the date  
strftime()  Returns a string representing the date, controlled by an explicit format string  
__format__()  Same as date.strftime(). This makes it possible to specify format string for a date object when using str.format()  
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