Subsetting columns
From the new database I just created, you can see how there are some columns that came with the original databases, which I do not need and do not I want to use. For this, you can create a new database with only the columns you want or delete the columns you do not like. Lets try.
Deleting columns
This is the simplest approach. Basically, I set the column I want to delete to NULL. Like this,
MergeData$X= NULL #with this code I delete the column called X, which is probably an index number used by one of the data sourcesNow, you try to delete the column “continent.x”.
Selecting columns
Obviously, if you have many columns that you do not need, deleting columns may take a while, as you have to type each column name you want to delete. Alternatively, you can simply select the columns you need. Like this,
This syntax should be familiar to you already. As it is the indexing function we used earlier [rows, columns].
If you read the code above, basically….I created a new database called SelectedColumns, which takes the database MergeData and select all rows (because there is nothing to the left of the comma) and the four columns listed in the vector after the comma.
## country year gdpPercap lifeExp
## 1 Afghanistan 1952 779.4453 28.801
## 2 Afghanistan 1957 820.8530 30.332
## 3 Afghanistan 1962 853.1007 31.997
## 4 Afghanistan 1967 836.1971 34.020
## 5 Afghanistan 1972 739.9811 36.088
## 6 Afghanistan 1977 786.1134 38.438f