What are the mistakes in this code, using R studio?

Question

 the statistician decides to use the processed dataset to calculate the mean DNA damage for each combination of conditions defined by cancer cell line, anti-cancer agent and concentration. There are ten replicate cases for each unique experimental condition. They try to use the following dplyr code to do this:

Summarised_Data <-

#// line 1

Results_Data %>%

#// line 2

group_by(Cell_Line, Agent) %>%

#// line 3

summarise(Mean_Damage = calculate_mean(DNA_Damage, na.rm = TRUE)

I have identified 3:

I think there is one error in line 1 as the wrong data frame is used

no errors in line 2 

2 errors in line 3 as there is a missing bracket and the function 'calculate_mean" doesnt exist 

please could someone advise if they agree or not

thanks 

Answer 1

Putting together pieces and guessing we have one dataframe containing the experimental data called Results_Data, with at least 4 variables (DNA_Damage, cell_line, agent, concentration) If one wants to get DNA_Damage means for all combinations of cell_line, agent, and concentration then there is a missing variable in the group_by() function call.

Results_Data - source data frame

Summarized_Data - data frame with means ( This is correctly referenced in the code as Results_Data is sent to group_by, then on to summarize, and finally to Summarized_Data)

This would be 3 errors.

#1 - if concentration is a factor, it should be included in the group_by() function call if one wants all combinations.

#2 - Line 3 is missing a right bracket ')' at the end of the line

#3 - calculate-mean is an undefined function. mean() should be used.

Summarised_Data <- Results_Data %>%

group_by(Cell_Line, Agent, Concentration) %>%

summarize(Mean_Damage = mean(DNA_Damage, na.rm = TRUE))