New Variable in Dataframe with pre-conditions

[Lukas1]

Hi guys,
I am quite new to R and probably have a tricky question for you that might also challenge some more advanced coders.

I want to create a variable that tells me, if any of the Friends of the persons come from the same country, then how much.
So in case of "Alex" the new column in the dataset should show 51% because 51% of his friends come from the same country, in this case "Austria"

In the case of Bob the column should show me in Bob's row that 10% come from the same country.

In case of Felicia it would be 0% because her friends do not come from the same country

Person Name	Person Country	Most friends come from	Most friends come from percent	Second most friends come from	Second most friends come from percent	Third most friends come from	Third most friends come from percent
Alex	Austria	Austria	51,00%	Sweden	12,00%	Norway	5,00%
Bob	Denmark	United States	14,00%	Denmark	10,00%	Spain	5,00%
Charlie	France	France	30,00%	Spain	15,00%	United States	12,00%
Diana	The Netherlands	Spain	32,00%	Sweden	28,00%	United States	10,00%
Eva	Finland	Sweden	60,00%	United States	20,00%	Finland	10,00%
Felicia	Germany	Austria	24,00%	United States	23,00%	Spain	17,00%

I would really appreciate it if you could help me with these lines of code because as a beginner I am quite overwhelmed with this task.

Thank you very much in advance,
Lukas

[StatSteph]

Hi Lukas,

Welcome! In the future, try to share your data in a reproducible fashion. It is not directly obvious how to get your example data into R. I was able to use datapasta but this isn't always the case. Learn about reproducible examples here:

• FAQ: What's a reproducible example (`reprex`) and how do I create one?
• FAQ: How to do a minimal reproducible example ( reprex ) for beginners

Anyways, on to the problem. I first had to convert some text to numbers and then the key to your problem was using case_when which is similar to a bunch of if-else statements.

library(tidyverse)


friend_country <- data.frame(
   stringsAsFactors = FALSE,
   Person.Name = c("Alex","Bob","Charlie",
                   "Diana","Eva","Felicia"),
   Person.Country = c("Austria","Denmark",
                      "France","The Netherlands","Finland",
                      "Germany"),
   Most.friends.come.from = c("Austria",
                              "United States","France","Spain","Sweden",
                              "Austria"),
   Most.friends.come.from.percent = c("51,00%","14,00%",
                                      "30,00%","32,00%","60,00%","24,00%"),
   Second.most.friends.come.from = c("Sweden","Denmark",
                                     "Spain","Sweden","United States",
                                     "United States"),
   Second.most.friends.come.from.percent = c("12,00%","10,00%",
                                             "15,00%","28,00%","20,00%","23,00%"),
   Third.most.friends.come.from = c("Norway","Spain",
                                    "United States","United States",
                                    "Finland","Spain"),
   Third.most.friends.come.from.percent = c("5,00%","5,00%",
                                            "12,00%","10,00%","10,00%","17,00%")
)

conv_percent <- function(x){
   str_replace_all(x, ",", ".") %>% parse_number() # in my country, . is used where you use , so I had to replace this
}

friend_country %>%
   mutate(
      Most.friends.come.from.percent=conv_percent(Most.friends.come.from.percent),
      Second.most.friends.come.from.percent=conv_percent(Second.most.friends.come.from.percent),
      Third.most.friends.come.from.percent=conv_percent(Third.most.friends.come.from.percent),
      Self.country.percent=case_when(
         Person.Country==Most.friends.come.from~Most.friends.come.from.percent,
         Person.Country==Second.most.friends.come.from~Second.most.friends.come.from.percent,
         Person.Country==Third.most.friends.come.from~Third.most.friends.come.from.percent,
         TRUE ~ 0
      )
   )
#>   Person.Name  Person.Country Most.friends.come.from
#> 1        Alex         Austria                Austria
#> 2         Bob         Denmark          United States
#> 3     Charlie          France                 France
#> 4       Diana The Netherlands                  Spain
#> 5         Eva         Finland                 Sweden
#> 6     Felicia         Germany                Austria
#>   Most.friends.come.from.percent Second.most.friends.come.from
#> 1                             51                        Sweden
#> 2                             14                       Denmark
#> 3                             30                         Spain
#> 4                             32                        Sweden
#> 5                             60                 United States
#> 6                             24                 United States
#>   Second.most.friends.come.from.percent Third.most.friends.come.from
#> 1                                    12                       Norway
#> 2                                    10                        Spain
#> 3                                    15                United States
#> 4                                    28                United States
#> 5                                    20                      Finland
#> 6                                    23                        Spain
#>   Third.most.friends.come.from.percent Self.country.percent
#> 1                                    5                   51
#> 2                                    5                   10
#> 3                                   12                   30
#> 4                                   10                    0
#> 5                                   10                   10
#> 6                                   17                    0

^{Created on 2021-12-20 by the reprex package (v2.0.1)}