Problems

• Write a function parse_csv which will load tables from file and return a 2D list as given below

  %%file tables.csv
  1,2,3,4,5
  2,4,6,8,10
  3,6,9,12,15
  4,8,12,16,20
  5,10,15,20,25
  6,12,18,24,30
  7,14,21,28,35
  8,16,24,32,40
  9,18,27,36,45
  10,20,30,40,50

if tables.csv contains above data, the function should work as given below

>>> parse_csv("tables.csv")
[[1, 2, 3, 4, 5],
 [2, 4, 6, 8, 10],
 [3, 6, 9, 12, 15],
 [4, 8, 12, 16, 20],
 [5, 10, 15, 20, 25],
 [6, 12, 18, 24, 30],
 [7, 14, 21, 28, 35],
 [8, 16, 24, 32, 40],
 [9, 18, 27, 36, 45],
 [10, 20, 30, 40, 50]]

• Write a class to represent our python classroom. the data encapsulation and methods look like this. assume all data is public. ```

           +----------------------------+
           |                            |
           |   student_names            |--------->get_score(name)
  names--->|   scores_for_assignment    |
           |                            |--------->assign_score(name, score)
           |                            |
           |                            |--------->get_average_score()
           |                            |
           +-----------------------------

text = "[1, 2, 3, 4, 5]"

%%file tables.csv
1,2,3,4,5
2,4,6,8,10
3,6,9,12,15
4,8,12,16,20
5,10,15,20,25
6,12,18,24,30
7,14,21,28,35
8,16,24,32,40
9,18,27,36,45
10,20,30,40,50

Overwriting tables.csv

row = "1,2,3,4,5"

row.split(",")

['1', '2', '3', '4', '5']

[int(item) for item in row.split(",")]

[1, 2, 3, 4, 5]

def parse_csv(filename):
    with open(filename) as f:
        data = []
        for line in f:
            rowdata = [int(item) for item in line.split(",")]
            data.append(rowdata)
        return data

parse_csv("tables.csv")

[[1, 2, 3, 4, 5],
 [2, 4, 6, 8, 10],
 [3, 6, 9, 12, 15],
 [4, 8, 12, 16, 20],
 [5, 10, 15, 20, 25],
 [6, 12, 18, 24, 30],
 [7, 14, 21, 28, 35],
 [8, 16, 24, 32, 40],
 [9, 18, 27, 36, 45],
 [10, 20, 30, 40, 50]]

def parse_csv(filename):
    """this will parse matrix of intengers from a file
    """
    with open(filename) as f:
        return [[int(item) for item in line.split(",")] for line in f]
        
    

parse_csv("tables.csv")

[[1, 2, 3, 4, 5],
 [2, 4, 6, 8, 10],
 [3, 6, 9, 12, 15],
 [4, 8, 12, 16, 20],
 [5, 10, 15, 20, 25],
 [6, 12, 18, 24, 30],
 [7, 14, 21, 28, 35],
 [8, 16, 24, 32, 40],
 [9, 18, 27, 36, 45],
 [10, 20, 30, 40, 50]]

f = open("tables.csv")

help(f.read)

Help on built-in function read:

read(size=-1, /) method of _io.TextIOWrapper instance
    Read at most n characters from stream.
    
    Read from underlying buffer until we have n characters or we hit EOF.
    If n is negative or omitted, read until EOF.

f.read(5) # read next 5 characters

'1,2,3'

f.read(10) # read next

',4,5\n2,4,6'

class PythonClassRoom:
    
    def __init__(self, names):
        self._scores = {}

names = ["A","B","C","D"]

scores = {}
for name in names:
    scores[name] = -1

scores

{'A': -1, 'B': -1, 'C': -1, 'D': -1}

{name:-1 for name in names} # dictionary comprehansion

{'A': -1, 'B': -1, 'C': -1, 'D': -1}

[int(item) for item in row.split(",")]

[1, 2, 3, 4, 5]

[1,2,3]
{"a":1, "b":2, "c":3}

class PythonClassRoom:
    
    def __init__(self, names):
        self._scores = {name:-1 for name in names}
        # we will store data as a dictionary
        # initialized it with -1 scores for all the student
        
    def get_score(self, name):
        return self._scores[name]
    
    def assign_score(self, name, score):
        self._scores[name] = score
          
    def get_average_score(self):
        s = 0
        count = 0
        for name,score in self._scores.items():
            if score >= 0:
                s += score
                count += 1
        return s/count
    
    
    def get_average_score(self):
        solved_scores = [score for name, score in self._scores.items() if score>=0]
        return sum(solved_scores)/len(solved_scores)

list("ABCDEF")

['A', 'B', 'C', 'D', 'E', 'F']

c = PythonClassRoom(list("ABCDEF")

c.get_score("A")

-1

c.assign_score("B", 80)

c.get_score("B")

80

c.get_average_score()

80.0

c.assign_score("C", 90)

c.get_average_score()

85.0

Working with CSV files

import csv

%%file data.csv
ticker,value,open,close,high,low
XEFD,123,124,125,127,120.0
RTRT,567,565,564,569,560.5
RTAT,567,565,564,569,560.4
RCRT,567,565,564,569,560.2
RTRT,567,565,564,569,560.1

Overwriting data.csv

parse_csv("data.csv") # our function does not handle column headers and also types of columns

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-45-dfaa2971ba09> in <module>
----> 1 parse_csv("data.csv") # our function does not handle column headers and also types of columns

<ipython-input-18-2464182c2bc5> in parse_csv(filename)
      3     """
      4     with open(filename) as f:
----> 5         return [[int(item) for item in line.split(",")] for line in f]
      6 
      7 

<ipython-input-18-2464182c2bc5> in <listcomp>(.0)
      3     """
      4     with open(filename) as f:
----> 5         return [[int(item) for item in line.split(",")] for line in f]
      6 
      7 

<ipython-input-18-2464182c2bc5> in <listcomp>(.0)
      3     """
      4     with open(filename) as f:
----> 5         return [[int(item) for item in line.split(",")] for line in f]
      6 
      7 

ValueError: invalid literal for int() with base 10: 'ticker'

import csv

def read_csv(filename):
    with open(filename) as f:
        csvreader = csv.reader(f)  # csvreader is ierator but instaed giving line as a text it gives list of fileds
        data = []
        for row in csvreader:
            data.append(row)
        return data

f = open("data.csv")
csvreader = csv.reader(f)

csvreader # it is an iterator

<_csv.reader at 0x7f00ca604510>

next(csvreader)

['ticker', 'value', 'open', 'close', 'high', 'low']

next(csvreader)

['XEFD', '123', '124', '125', '127', '120.0']

def read_csv(filename):
    with open(filename) as f:
        csvreader = csv.reader(f)  # csvreader is iterator but instaed giving line as a text it gives list of fileds
        data = []
        headers = next(csvreader) # read headers seperately
        for row in csvreader:
            data.append(row)
        return headers, data

headers, data  = read_csv("data.csv")

headers

['ticker', 'value', 'open', 'close', 'high', 'low']

data

[['XEFD', '123', '124', '125', '127', '120.0'],
 ['RTRT', '567', '565', '564', '569', '560.5'],
 ['RTAT', '567', '565', '564', '569', '560.4'],
 ['RCRT', '567', '565', '564', '569', '560.2'],
 ['RTRT', '567', '565', '564', '569', '560.1']]

 file              -> f (open)  ->  csvreader (csv.reader(f)
------------------   ----------  ----------------
  ++++++++++++++++       +         +                --> one line out
------------------   ----------  ----------------

items = [1, 2, 3, 4]
# for loop is working this logic
items_  = iter(items)
next(items_)
next(items_)
next(items_)

3

next(items_)

4

next(items_)

---------------------------------------------------------------------------
StopIteration                             Traceback (most recent call last)
<ipython-input-22-9ef95e9998b4> in <module>
----> 1 next(items_)

StopIteration: 

def read_csv(filename):
    with open(filename) as f:
        csvreader = csv.reader(f)  # csvreader is iterator but instaed giving line as a text it gives list of fileds
        data = []
        #headers = next(csvreader) # read headers seperately
        for row in csvreader:
            data.append(row)
        return data

read_csv("data.csv")

[['ticker', 'value', 'open', 'close', 'high', 'low'],
 ['XEFD', '123', '124', '125', '127', '120.0'],
 ['RTRT', '567', '565', '564', '569', '560.5'],
 ['RTAT', '567', '565', '564', '569', '560.4'],
 ['RCRT', '567', '565', '564', '569', '560.2'],
 ['RTRT', '567', '565', '564', '569', '560.1']]

def read_csv(filename, fields):
    with open(filename) as f:
        csvreader = csv.reader(f)  # csvreader is iterator but instaed giving line as a text it gives list of fileds
        data = []
        headers = next(csvreader) # read headers seperately
        for row in csvreader:#iterator, so at a time one list comes
            converted_row = [convert(item) for item, convert in zip(row, fields)]
            data.append(converted_row)
        return headers, data

read_csv("data.csv", [str, int, int, float, float, float])

(['ticker', 'value', 'open', 'close', 'high', 'low'],
 [['XEFD', 123, 124, 125.0, 127.0, 120.0],
  ['RTRT', 567, 565, 564.0, 569.0, 560.5],
  ['RTAT', 567, 565, 564.0, 569.0, 560.4],
  ['RCRT', 567, 565, 564.0, 569.0, 560.2],
  ['RTRT', 567, 565, 564.0, 569.0, 560.1]])

row = ['XEFD', '123', '124', '125', '127', '120.0']
fields  = [str, int, int, float, float, float]

for item, convert in zip(row, fields):
    print(convert(item))

XEFD
123
124
125.0
127.0
120.0

[convert(item) for item, convert in zip(row, fields)]

['XEFD', 123, 124, 125.0, 127.0, 120.0]

fields = [("value", float),
          ("open", float),
          ("close", float),
          ("high", float),
          ("low", float)
         ]

with open("data.csv") as f:
    csvdict = csv.DictReader(f)
    for row in csvdict:
        print(row)

{'ticker': 'XEFD', 'value': '123', 'open': '124', 'close': '125', 'high': '127', 'low': '120.0'}
{'ticker': 'RTRT', 'value': '567', 'open': '565', 'close': '564', 'high': '569', 'low': '560.5'}
{'ticker': 'RTAT', 'value': '567', 'open': '565', 'close': '564', 'high': '569', 'low': '560.4'}
{'ticker': 'RCRT', 'value': '567', 'open': '565', 'close': '564', 'high': '569', 'low': '560.2'}
{'ticker': 'RTRT', 'value': '567', 'open': '565', 'close': '564', 'high': '569', 'low': '560.1'}

fields = [("value", float),
          ("open", float),
          ("high", float),
          ("low", float)
         ]

with open("data.csv") as f:
    csvdict = csv.DictReader(f) # it makes used of column headers to create dictionary for evry row
    for row in csvdict:
        row.update((colname, convert(row[colname])) for colname, convert in fields)
        print(row)

{'ticker': 'XEFD', 'value': 123.0, 'open': 124.0, 'close': '125', 'high': 127.0, 'low': 120.0}
{'ticker': 'RTRT', 'value': 567.0, 'open': 565.0, 'close': '564', 'high': 569.0, 'low': 560.5}
{'ticker': 'RTAT', 'value': 567.0, 'open': 565.0, 'close': '564', 'high': 569.0, 'low': 560.4}
{'ticker': 'RCRT', 'value': 567.0, 'open': 565.0, 'close': '564', 'high': 569.0, 'low': 560.2}
{'ticker': 'RTRT', 'value': 567.0, 'open': 565.0, 'close': '564', 'high': 569.0, 'low': 560.1}

def get_column(filename, name, type_):
    with open(filename) as f:
        return [type_(row[name]) for row in csv.DictReader(f)]

get_column("data.csv", "value", int)

[123, 567, 567, 567, 567]

get_column("data.csv", "low", float)

[120.0, 560.5, 560.4, 560.2, 560.1]

get_column("data.csv", "ticker", str)

['XEFD', 'RTRT', 'RTAT', 'RCRT', 'RTRT']

d_dict = {"A":1,"B":2}

c_dict = {"B":5}

d_dict.update(c_dict)

d_dict

{'A': 1, 'B': 5}

d_dict.update([("A",-1)])

d_dict

{'A': -1, 'B': 5}

def write_data(data, columns, filename):
    with open(filename, "w") as f:
        csvf =csv.writer(f)
        csvf.writerow(columns)
        for row in data:
            csvf.writerow(row)

data = [[rows*col for col in range(5)] for rows in range(10)]

data

[[0, 0, 0, 0, 0],
 [0, 1, 2, 3, 4],
 [0, 2, 4, 6, 8],
 [0, 3, 6, 9, 12],
 [0, 4, 8, 12, 16],
 [0, 5, 10, 15, 20],
 [0, 6, 12, 18, 24],
 [0, 7, 14, 21, 28],
 [0, 8, 16, 24, 32],
 [0, 9, 18, 27, 36]]

import random
data = [[random.random() for col in range(5)] for rows in range(10)]

data

[[0.7057121257994273,
  0.7864947876735638,
  0.7621844085351732,
  0.9654831014981514,
  0.3567076740124062],
 [0.8881837712562509,
  0.009969080535370933,
  0.1288604952939728,
  0.1265945416544907,
  0.8881304892937462],
 [0.21416500435784458,
  0.377220868684886,
  0.33887937806712065,
  0.8746205901452834,
  0.6419031745768445],
 [0.12528488716551545,
  0.759774674371733,
  0.7126177864936741,
  0.8896953259123864,
  0.7175395149165447],
 [0.44668238950194983,
  0.8088345273508774,
  0.31607359717114136,
  0.8553760127948428,
  0.1539282717724595],
 [0.2693476517014519,
  0.5667763900580283,
  0.28807786366283916,
  0.9799392699110685,
  0.30814778875585935],
 [0.04268773711804652,
  0.49158989964390776,
  0.06243347585628645,
  0.3868720211773563,
  0.20015010068644956],
 [0.4816950723359398,
  0.12721392333502135,
  0.5069635425148686,
  0.7357301719824074,
  0.7185830726043789],
 [0.4981850311695367,
  0.6921429602517064,
  0.5359832693913509,
  0.11662775529322034,
  0.4055794030279445],
 [0.23563399202027602,
  0.05107382507494951,
  0.9916845405560221,
  0.26444034569390906,
  0.9271757106601667]]

write_data(data, list("ABCDE"), "random.csv")

!python cat.py random.csv

A,B,C,D,E
0.7057121257994273,0.7864947876735638,0.7621844085351732,0.9654831014981514,0.3567076740124062
0.8881837712562509,0.009969080535370933,0.1288604952939728,0.1265945416544907,0.8881304892937462
0.21416500435784458,0.377220868684886,0.33887937806712065,0.8746205901452834,0.6419031745768445
0.12528488716551545,0.759774674371733,0.7126177864936741,0.8896953259123864,0.7175395149165447
0.44668238950194983,0.8088345273508774,0.31607359717114136,0.8553760127948428,0.1539282717724595
0.2693476517014519,0.5667763900580283,0.28807786366283916,0.9799392699110685,0.30814778875585935
0.04268773711804652,0.49158989964390776,0.06243347585628645,0.3868720211773563,0.20015010068644956
0.4816950723359398,0.12721392333502135,0.5069635425148686,0.7357301719824074,0.7185830726043789
0.4981850311695367,0.6921429602517064,0.5359832693913509,0.11662775529322034,0.4055794030279445
0.23563399202027602,0.05107382507494951,0.9916845405560221,0.26444034569390906,0.9271757106601667

class Light:
    
    def __init__(self):
        self._status = False
        
    def swicthon(self):
        self._status = True
    
    def swicthoff(self):
        self._status = True
    
    def status(self):
        return self._status
    
class YellowLight(Light): # inheritence  ..YellowLight is child and Light is parent
    color = "Yellow" # class variable
    

y1 = YellowLight()

y1.status()

False

y1.color

'Yellow'

y2 = YellowLight()

class ColouredLight(Light):
    
    def __init__(self, color):
        self._status = False
        self._color = color
        
    def change_colur(self, color):
        self._color = color
        
        
    def get_color(self):
        return self._color

c1 = ColouredLight("yellow")

c2 = ColouredLight("red")

c1.get_color()

'yellow'

c2.get_color()

'red'

y1.color

'Yellow'

y2.color

'Yellow'