Julia：DataFrame簡介
阿新 • • 發佈：2018-11-06
using DataFrames showln(x) = (show(x); println()) # 這句程式碼很重要 # A DataFrame is an in-memory database df = DataFrame(A = [2, 5], B = [e, pi], C = ["x", "y"]) showln(df) #> 2x3 DataFrame #> |-------|---|---------|------| #> | Row # | A | B | C | #> | 1 | 1 | 2.71828 | "xx" | #> | 2 | 2 | 3.14159 | "xy" | # The columns of a DataFrame can be indexed using numbers or names showln(df[1]) #> [2,5] showln(df[:A]) #> [2,5] showln(df[2]) #> [2.718281828459045,3.141592653589793] showln(df[:B]) #> [2.718281828459045,3.141592653589793] showln(df[3]) #> String["x","y"] showln(df[:C]) #> String["x","y"] # The rows of a DataFrame can be indexed only by using numbers showln(df[1, :]) #> 1x3 DataFrame #> |-------|---|---------|------| #> | Row # | A | B | C | #> | 1 | 2 | 2.71828 | "x" | showln(df[1:2, :]) #> 2x3 DataFrame #> |-------|---|---------|------| #> | Row # | A | B | C | #> | 1 | 2 | 2.71828 | "x" | #> | 2 | 5 | 3.14159 | "y" |