Menu
If I have a dataframe like:
test = DataFrame(A = [1,2,3] , B= [4,5,6])
and I want to change only the name of A, what can I do? I know that I can change the name of all columns together by rename! but I need to rename one by one. The reason is that I'm adding new columns by hcat in a loop and need to give them unique names each time.
654
asked Oct 15 '20 12:10
To rename a column or columns, you need to use rename , or rename! . The difference is that rename creates a new data frame with the updated name(s) whereas rename! modifies the name(s) in-place. If you have a lot of columns to rename, it might be better to use a Dict .
To change a column name, enter the following statement in your MySQL shell: ALTER TABLE table_name RENAME COLUMN old_column_name TO new_column_name; Replace table_name , old_column_name , and new_column_name with your table and column names.
By default, Julia doesn't print all the rows and columns of a DataFrame because of obvious reasons like space and storage issues. But if you want to see all the rows and columns, it's possible using show() function with allrows & allcols arguments.
Use the Pair syntax:
julia> test = DataFrame(A = [1,2,3] , B= [4,5,6])
3×2 DataFrame
│ Row │ A │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
julia> rename!(test, :A => :newA)
3×2 DataFrame
│ Row │ newA │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
julia> test
3×2 DataFrame
│ Row │ newA │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
With strings it is the same:
3×2 DataFrame
│ Row │ A │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
julia> rename!(test, "A" => "newA")
3×2 DataFrame
│ Row │ newA │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
julia> test
3×2 DataFrame
│ Row │ newA │ B │
│ │ Int64 │ Int64 │
├─────┼───────┼───────┤
│ 1 │ 1 │ 4 │
│ 2 │ 2 │ 5 │
│ 3 │ 3 │ 6 │
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
