IDL可视化入门与提高(3)

IDL> ;跨越两个维度的下标 IDL> print,arr[0:2,0:1] 0 2 4 10 12 14

2.4.3一维下标

无论数组的维数是多少，它总可以用一位数组来表示。也就是说，用户可以设置一个特定的下标，从零开始按多维数组中存储元素的顺序来标记多维数组中的每个元素

IDL> arr = indgen(5,3)*1 IDL> print,arr

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 IDL> ;取元素6 IDL> print,arr[1,1] 6

IDL> print,arr[4] 4

IDL> print,arr[6] 6

2.4,5多维下标的抽取

IDL> n = 5

IDL> arr = indgen(n,n) IDL> print,arr

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 IDL>

IDL> index = lindgen((n+1)/2)*2 IDL> print,index

0 2 4 IDL> print,arr[index] 0 2 4 IDL> print,arr[index,index] 0 12 24 IDL> sub = arr[*,index] IDL> print,sub

0 1 2 3 4 10 11 12 13 14 20 21 22 23 24 IDL> sub = sub[index,*] IDL> print,sub

0 2 4 10 12 14 20 22 24

IDL> sub = (arr[*,index])[*,index] IDL> print,sub

0 1 2 3 4 20 21 22 23 24 20 21 22 23 24