we will continue working with LaqnData.csv:

a$)$ Run the following code, see its output, and then study the copde to answer what each line of this code does:

air$\_$df$=$pd$.$read$\_$csv$(\text{'}$LaqnData$.$csv$\text{'})$

air$\_$df$.$drop$($columns$=["$Site$\text{'},$'Units','Provisional or Ratified'$],$ inplace$=$True$)$

datetime$\_$df$=$air$\_$df$.$readingDatetime.str$.$split$(\text{'}\text{'},$expand$=$True$)$

datetime$\_$df$.$columns$=[\text{'}$Date$\text{'},$'Time$]$

date$\_$df$=$datetime$\_$df$.$Date.str$.$split$(\text{'}/\text{'},$expand$=$True$)$

date$\_$df$.$columns$=[\text{'}$Day$\text{'},$'Month','Year'$]$

air$\_$df$=$air$\_$df$.$join$($date$\_$df$.$join$($datetime$\_$df$.$Time$).$drop$($columns$=[\text{'}$ReadingDateTime$\text{'},$'Year'$])$

air$\_$df

b$)$ run the following code, see its output, and then study the code to answer what this line of code does:

air$\_$df$=$air$\_$df$.$set$\_$index$([\text{'}$Month$\text{'},$'Day','Time','Species'$])$

air$\_$df

c$)$ run the following code, see its output, and then study the code to answer what this line of code does:

air$\_$df$.$unstack$()$

d$)$ compare the output of the preceding code with pvt$\_$df from Exercise $4.$ are they the same?

e$)$explain what the differences and similarities are between the pair $.$melt$()/.$pivot$()$ and the pair $.$stack$()/.$unstack$()?$

f$)$ if you were to choose one counterpartr for $.$melt$()$ between $.$stack$()/.$unstack$(),$ which one would you choose?