R/Shiny: Transpose and add data to Dataframe-CodePudding

I'm trying to figure out a way to transpose data and then add that data to a seperate dataframe.

I have

Column 1 | Column 2| Column 3
________________________________
Data 1   | Data 2  | Data 3

And in a seperate data frame I have

actualColumn1| actualColumn2
________________________________
Column 1   | otherData 2   
Column 2   | otherData 2   
Column 3   | otherData 2

And want to get to:

actualColumn1| actualColumn2|addedData
________________________________
Column 1   | otherData 2 | Data 1  
Column 2   | otherData 2 | Data 2  
Column 3   | otherData 2 | Data 3

Since the column names from the first dataframe correspond perfectly to the rows in actualcolumn1. I apologize if I didn't explain this very well. I'm still new to R/Shiny and dataframe manipulation.

CodePudding user response：

You can reshape the dataframe to have the 1 observation of 3 variables to 1 variable with 3 observations using pivot_longer(), then join to the other dataframe.

library(tidyverse)

df1 %>% 
  mutate(x = 1) %>% 
  pivot_longer(cols = -x, names_to = "actualColumn1", values_to = "addedData") %>% 
  select(-x) %>% 
  left_join(x = df2, y = .)

# Joining, by = "actualColumn1"
#    actualColumn1 actualColumn2 addedData
# 1:      Column 1   otherData 2    Data 1
# 2:      Column 2   otherData 2    Data 2
# 3:      Column 3   otherData 2    Data 3

Data:

df1 <- data.table::fread("Column 1 | Column 2| Column 3
Data 1   | Data 2  | Data 3   ")

df2 <- data.table::fread("actualColumn1| actualColumn2
Column 1   | otherData 2   
Column 2   | otherData 2   
Column 3   | otherData 2   ")