对具有不同条件的五个或更多列进行子集化 R data.table

Question

I have a data.table that looks like this:

 COUNTRY   GENDER     CURRENCY    INCOME_GROUP    YEAR  
 FRANCE     MAN       EURO            HIGH        2014  
 GERMANY    WOMEN     EURO            LOW         2015  
 FINLAND    MAN       EURO            LOW         2016  
 JAPAN      MAN       YEN             HIGH        2017  
 USA        WOMEN     DOLLAR          LOW         2018  

I want to subset this table with this code: datanew <- data[data$YEAR == "2014"& data$CURRENCY == "DOLLAR" & data$COUNTRY == FRANCE & data$INCOME_GROUP == LOW] but whenever I add three or more condition datanew variable always has "0" observation. I mean I can not add 4 or more conditions. Is there any way to solve this problem? Thanks for your help.

Answer 1

I'm presuming you are wanting to subset rows which fulfil the criteria you gave? In that case, there aren't any rows which satisfy your criteria.

If you try:

data = fread('COUNTRY   GENDER     CURRENCY    INCOME_GROUP    YEAR  
 FRANCE     MAN       EURO            HIGH        2014  
 GERMANY    WOMEN     EURO            LOW         2015  
 FINLAND    MAN       EURO            LOW         2016  
 JAPAN      MAN       YEN             HIGH        2017  
 USA        WOMEN     DOLLAR          LOW         2018  
')

data[YEAR == "2014" & CURRENCY == "EURO" & COUNTRY == "FRANCE" & INCOME_GROUP == "HIGH"]

returns:

   COUNTRY GENDER CURRENCY INCOME_GROUP YEAR
1:  FRANCE    MAN     EURO         HIGH 2014

Also, you need to wrap quotes around FRANCE and LOW in your statement, and since it's a data.table , you don't need to use the dollar sign for identifying the columns.

Answer 2

Your code doesn't replicate the error, running your code the error is:

Error in `[.data.frame`(data, data$YEAR == "2014" & data$CURRENCY == "DOLLAR" &  : 

object 'FRANCE' not found

This is because you are trying to call a variable called FRANCE (and another called LOW) when you should be passing a character vector, like you do with "DOLLAR" :

datanew <- data[data$YEAR == "2014"& data$CURRENCY == "DOLLAR" & data$COUNTRY == "FRANCE" & data$INCOME_GROUP == "LOW"]

This replicates your problem, data frame with 0 columns and 5 rows which is just that you have no rows that satisfy all conditions - you subset to no data. You can have as many conditions as you like, but you need data that satisfy them. The following returns one row:

data[data$YEAR == "2014"& data$CURRENCY == "EURO" & data$COUNTRY == "FRANCE" & data$INCOME_GROUP == "HIGH"]