为数组索引多个级别时,它可以正常工作.但是当我用它来分配值时,却没有.有谁知道为什么A不在下面改变？
In [4]: A = rand(6)
Out [4]: 6-element Array{Float64,1}:
0.111552
0.155126
0.78485
0.147477
0.362078
0.959022
In [5]: A[3:5][[true,false,true]]
Out [5]: 2-element Array{Float64,1}:
0.78485
0.362078
In [6]: A[3:5][[true,false,true]] = [99, 999]
Out [6]: 2-element Array{Int64,1}:
99
999
In [7]: A
Out [7]: 6-element Array{Float64,1}:
0.111552
0.155126
0.78485
0.147477
0.362078
0.959022
I am trying to change type of numbers in a column of a DataFrame from integer to floating point. It should be straightforward to do this, but it's not working. The data type remains to be integer. What am I missing?
In [2]: using DataFrames
df = DataFrame(A = 1:4, B = ["M", "F", "F", "M"])
Out [2]: 4x2 DataFrame
| Row | A | B |
|-----|---|-----|
| 1 | 1 | "M" |
| 2 | 2 | …