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# Core Designer Certificate: HOL Question 5

Registered Posts: 5

I'm stuck on question 5! My formal is correct but there is no data showing up in the column. I successfully created a card for Univariate analysis of the 3 categories but don't know what I'm missing. Any guidance would be greatly appreciated. I'm applying for a sales position and would love to be certified prior to the interview process starting.

Some columns ( Oil production (Etemad & Luciana) (terawatt-hours), meat_prod_tonnes, and Food Balance Sheets: Eggs - Production (FAO (2017)) (tonnes) ) report country total data. Transform these three columns into per-capita data.

• Hint 1: To convert from country “total” data to “per-capita” data divide by the country's population.
• Hint 2: The Formula page in the reference documentation shows the proper syntax for using formulas to read column values when the column names include spaces.
• Hint 3: You will not need the original columns (including Population) for further analysis.

Thanks!

AA

• Registered Posts: 5

Here's the formula I used numval("Oil production (Etemad & Luciana) (terawatt-hours)") / numval(Population) - DSS says the formula is valid but I'm this ExpressionError: Cannot parse to number: null in the sample output column. What am I missing? I tired to apply the formula to the whole dataset then on the individual columns and got nothing

• Dataiker, Dataiku DSS Core Designer, Dataiku DSS ML Practitioner, Dataiku DSS Adv Designer, Registered Posts: 19 Dataiker

,

I would suggest looking at the names of your columns and which ones need to be converted using numval.

Hope that helps!

Best,

• Registered Posts: 5

Thanks for the tip. I'll apply and see what happens

• Registered Posts: 5

curious if rounding to integers is the first right step or does that skew the data? @denisemalan

• Dataiku DSS Core Designer, Registered Posts: 1

Hello, I am also having the same problem. I tried isolating the variables that needed to be converted using numval but that still didn't work. This is what I have so far:

numval("Oil production (Etemad & Luciana) (terawatt-hours)")/(Population)

• Dataiker, Dataiku DSS Core Designer, Dataiku DSS ML Practitioner, Dataiku DSS Adv Designer, Registered Posts: 19 Dataiker

Hi, @LeBronJames,

This formula works for me. Keep in mind the Oil production column has some nulls so you won't see output for every row.

Best,

Denise

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