Notes

- List m[1,2,3,4,5,6,7,8,9,10] What does this do m[1:9:-2]
- Data type in python ?
- What is an exception. Conversion with exception try catch
def convertInt(instring):
try :
return int(instring)
except:
return -1
- define a class with an attribute name, age and a method change_name to change its name
class Dog:
def __init__(self, name, age):
self.name = name
self.age = age
def change_name(self, new_name):
self.name = new_name

Define a Dog object named "Oscar"
Change the name of this Dog to "Enzo"

-What is regex. What does this regex do ?

>>> df = pd.DataFrame([[4, 9]] * 3, columns=['A', 'B'])
>>> df
A B
0 4 9
1 4 9
2 4 9

#try math to see if work
>>> df.apply(np.sqrt)
A B
0 2.0 3.0
1 2.0 3.0
2 2.0 3.0

>>> df.apply(np.sum, axis=0)
A 12
B 27
dtype: int64

>>> df.apply(np.sum, axis=1)
0 13
1 13
2 13
dtype: int64

>>> df.apply(lambda x: [1, 2], axis=1)
0 [1, 2]
1 [1, 2]
2 [1, 2]

-Data frame : df with columns : ID, FirstName, LastName, NumberOfTransactions, AccountBalance, PhoneNumber, PostalCode, Email, Address
a. Convert Last Name to upper df["LastName"]=df["LastName"].upper()
b. Create FullName column with FirstName concatenated with LastName seperated by a space df["FullName"]=df["FirstName"]+' '+df["LastName"]
c. Use function ConvertInt above to clean the NumberOfAccounts columns. Column may contain values such as 1.0; 2,0; "NA"
d. Order customer by decreasing order of NumberOfTransactions, stored in df_sort
e. From the result of df_sort, select the top 5 customers with the highest number of transaction, create a simple report : "Top 5 customers with highest number of transactions are John SMITH, Mary CLAIR, Henry FORD, Bill SUMMER, Nicholas TESLA". Please consider a method that does not involve manually appending one customer after another, as it will not be scalable to respond to the question "top 1000 customers" instead of "top 5" df["FullName"].tolist() or list(df["FullName"]) then ','.join()
f.regex extract phone region from number (437) 226
g. Convert "20191130" to format "2019-11-30"
h. join
i. summary partition window function

-Dataframe Join
-What is Spark UDF, Spark dataframe, lazy evaluation ?