General Python Coding questions

Question 1

How do you determine if a number is divisible by three

Answer 1

num % 3 == 0

Question 2

Round a number up

Answer 2

math.ceil(n)

Question 3

How do you square a number

Answer 3

5**2

Question 4

how to run a math equation?

Answer 4

eval(“1+3==4”)

Question 5

how to replace a string character with a different character

Answer 5

“xyz”.replace(‘z’,’q’)
result: “xyq”

Question 6

How to extract a list value into another list

Answer 6

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

Question 7

How to write a sting in lower case

Answer 7

‘ABC’.lower()

Question 8

What does sub() do

Answer 8

finds all substrings where the regex pattern matches and then replace them with a different string

Question 9

what does subn() do

Answer 9

similar to sub but retuns the new sting along with the number of replacements

Question 10

How to remove values from a python array

Answer 10

pop() and remove()
pop return the value removed
remove does not return a value

Question 11

How to import modules in python

Answer 11

import array #importing using the original module name
import array as arr # importing using an alias name
from array import * #imports everything present in the array module

Question 12

What is polymorphism in python

Answer 12

Polymorphism means the ability to take multiple forms. for instance if the parent class has a method named ABC then the child class also can have a method with the same name ABC having its own parameters and variables. Python allows this

Question 13

What is used for floor division

Answer 13

//

Question 14

What is the maximum possible length of an identifier

Answer 14

Identifiers can be of any length

Question 15

how to tell if a file or directory exists?

Answer 15

os.path.exists(‘path’)

Question 16

How to open a file

Answer 16

with open(‘file path’, ‘r’) as f:
—x = f.read()

With automatically closes the file

Question 17

how to write a file

Answer 17

with open(‘file path’, ‘w’) as f:
—-f.write(‘text string here’)

this will create a new file if it doesn’t exist and over write that file if it already exists.

Question 18

How to turn a pandas column into a list

Answer 18

df[“column”].tolist()

Question 19

how to change pandas column type

Answer 19

df[‘column’].astype(‘str’)

Question 20

In a pandas loc statement what symbol reverses true?

Answer 20

~

Question 21

List comprehension

Answer 21

[x for x in [values] if x > 3]

Question 22

Finding quick general stats about a pandas dataframe

Answer 22

df.describe()

Question 23

Find the dataframes datatypes

Answer 23

df.dtypes

Question 24

List number of rows and columns in a pandas dataframe

Answer 24

df.shape

Question 25

list columns in a pandas dataframe

Answer 25

df.columns

Question 26

list general information about a pandas dataframe

Answer 26

df.info()

Question 27

how to get ride of duplicate rows

Answer 27

df.drop_duplicates()

Question 28

Finding the total number of null values in a dataframe

Answer 28

loadmatch.isna().sum()

loadmatch.isna().any()

Question 29

getting rid of a panda series rows

Answer 29

df.series.dropna()

Question 30

methods for filtering data that is greater than or less than a specific number.

Answer 30

.le()
.ge()
ex: df.loc[df.column.ge(2000)]

Question 31

filter dataframe where column contains certain values

Answer 31

.isin()
df.loc[df.column.isin([‘van’,’Reefer’)]

Question 32

symbols for AND and OR in pandas loc

Answer 32

&, |

Question 33

Pandas, Count the frequency a value appears in a column

Answer 33

.value_count()
ex: df[‘column’].value_count()

Question 34

How to group and aggreagate data

Answer 34

groupby() and aggregate()

df.groupby([“Mode”, “MonthName”]).agg({“Rate”:”sum”})

Question 35

Pandas Example of creating a new column

Answer 35

df.loc[loadmatch.Rate.le(100), “RateCategory”] = “Low”
This will add low to where the filter is set.

Question 36

Pandas how to inner join columns by their indexes

Answer 36

.join()
ex: df.join(df2, how=”inner”)
—-these will join based on the index set.

Question 37

Pandas how to combine data frames by specifying the columns

Answer 37

pd.merge()
ex: pd.merge(dataset1, dataset2, on=”Loadnum”, how=”inner)
ex: pd.merge(dataset1, dataset2,
left_on=[“loadnum”, “ActivityDate”, right_on=[“Loadnum”,
“ActivityDate”], how=”left”)