a*******r
发帖数: 7558 | 1 【 以下文字转载自 Computation 讨论区 】
发信人: alligator (侏罗纪的幸存者), 信区: Computation
标 题: IDL一问
发信站: BBS 未名空间站 (Mon Apr 30 22:10:00 2007)
我需要做些IDL的操作，例如
result=b1*0.0 & ix=where(b1 NE 0.0)
result(ix)=b2(ix)/b1(ix)
现在想弄个loop，对一批数据做上述处理：
b3(ix)/b1(ix), b4/b1,.... bn/b1
如果是igor之类的，可以很容易用类似于
String/G b_n="b"+num2str(n)
variable n=1
do
result=$band_name_n/b1
n+=1
while(...)
有谁知道 IDL 里该怎样进行此类循环? 我翻了IDL手册但没有找到
对应的number_to_string 函数，虽然google到一个num2str.pro | n**l
发帖数: 38 | 2 string()
【在 a*******r 的大作中提到】
: 【 以下文字转载自 Computation 讨论区 】
: 发信人: alligator (侏罗纪的幸存者), 信区: Computation
: 标 题: IDL一问
: 发信站: BBS 未名空间站 (Mon Apr 30 22:10:00 2007)
: 我需要做些IDL的操作，例如
: result=b1*0.0 & ix=where(b1 NE 0.0)
: result(ix)=b2(ix)/b1(ix)
: 现在想弄个loop，对一批数据做上述处理：
: b3(ix)/b1(ix), b4/b1,.... bn/b1
: 如果是igor之类的，可以很容易用类似于
| G*******s
发帖数: 76 | 3 IDL里面为了效率，一般避免用loop,lz的计算貌似可以避免loop
【在 a*******r 的大作中提到】
: 【 以下文字转载自 Computation 讨论区 】
: 发信人: alligator (侏罗纪的幸存者), 信区: Computation
: 标 题: IDL一问
: 发信站: BBS 未名空间站 (Mon Apr 30 22:10:00 2007)
: 我需要做些IDL的操作，例如
: result=b1*0.0 & ix=where(b1 NE 0.0)
: result(ix)=b2(ix)/b1(ix)
: 现在想弄个loop，对一批数据做上述处理：
: b3(ix)/b1(ix), b4/b1,.... bn/b1
: 如果是igor之类的，可以很容易用类似于
| a*******r
发帖数: 7558 | 4 how to do bn/b1 for n=1,2,.. w/o loop?
【在 G*******s 的大作中提到】
: IDL里面为了效率，一般避免用loop,lz的计算貌似可以避免loop
| a*******r
发帖数: 7558 | 5 3x
my data array are b1, b2, b3,...b100...
To do operations like b2/b1, b3/b1,...., I first do this:
for i=1, n do begin
my_data='b'+strtrim(string(i),1)
endfor
Now the string my_data has become b1, b2,..., but how to
convert the string my_data to the actual data b1, b2...?
【在 n**l 的大作中提到】
: string()
| G*******s
发帖数: 76 | 6 suppose your Bi(b1, b2...) is a vector(not necessarily a vector though), and
the number of elements in each vector are the same, then you can
store all data to a 2-dim array by the following,
dim b_all[n_elements(b1), number_of_BIs] as your_data_type
b_all = [b1,b2... bn] ; if n is large, do a loop
now you can do whatever operation you need
btw,you may use temporary(Bi) to improve efficiency and save memory
【在 a*******r 的大作中提到】
: 3x
: my data array are b1, b2, b3,...b100...
: To do operations like b2/b1, b3/b1,...., I first do this:
: for i=1, n do begin
: my_data='b'+strtrim(string(i),1)
: endfor
: Now the string my_data has become b1, b2,..., but how to
: convert the string my_data to the actual data b1, b2...?
| a*******r
发帖数: 7558 | 7 Thank you very much!
and
【在 G*******s 的大作中提到】
: suppose your Bi(b1, b2...) is a vector(not necessarily a vector though), and
: the number of elements in each vector are the same, then you can
: store all data to a 2-dim array by the following,
: dim b_all[n_elements(b1), number_of_BIs] as your_data_type
: b_all = [b1,b2... bn] ; if n is large, do a loop
: now you can do whatever operation you need
: btw,you may use temporary(Bi) to improve efficiency and save memory
| G*******s
发帖数: 76 | 8 my previous post is a workaround by avoiding the problem. however,
it could be solved in IDL.
first, please let me know weather i have got your question correctly. To
rephrase your question, 'how to access a variable with its string name?'am i
right?
if yes, one of the solutions is to use execute() function. check online
help
plz.
【在 a*******r 的大作中提到】
: Thank you very much!
:
: and
| a*******r
发帖数: 7558 | 9 let's say:
>b1=[1., 2., 3.]
>a='b'
>c=1
>d=a+num2str(c)
>print, d
b1
>e='print,b[1]'
>r=execute(e)
2.0000
I need to use string d (b1) to call array b1, how can I achieve
this in IDL?
i
【在 G*******s 的大作中提到】
: my previous post is a workaround by avoiding the problem. however,
: it could be solved in IDL.
: first, please let me know weather i have got your question correctly. To
: rephrase your question, 'how to access a variable with its string name?'am i
: right?
: if yes, one of the solutions is to use execute() function. check online
: help
: plz.
| G*******s
发帖数: 76 | 10 pro test
b1 = [1.,2.,3.]
for i = 0, n_elements(b1) -1 do begin
r = execute ( 'b_tmp = b1[' + strtrim(string(i),2) + ']' )
print, b_tmp
endfor
end
【在 a*******r 的大作中提到】
: let's say:
: >b1=[1., 2., 3.]
: >a='b'
: >c=1
: >d=a+num2str(c)
: >print, d
: b1
: >e='print,b[1]'
: >r=execute(e)
: 2.0000
| G*******s
发帖数: 76 | 11 要是你的字符串'b1'中的'1'也是动态生成的，也是一样的。类似很多其他语言里的根据
变量名字符串做个宏替换得到真正的变量。
pro test
b1 = [1.,2.,3.]
for j = 1, 1 do begin
str_of_var = 'b' + strtrim(string(j),2)
endfor
for i = 0, n_elements(b1) -1 do begin
r = execute ( 'b_tmp = ' + str_of_var + '[' + strtrim(string(i),2) +
']' )
print, b_tmp
endfor
end
【在 G*******s 的大作中提到】
: pro test
: b1 = [1.,2.,3.]
: for i = 0, n_elements(b1) -1 do begin
: r = execute ( 'b_tmp = b1[' + strtrim(string(i),2) + ']' )
: print, b_tmp
: endfor
: end
| a*******r
发帖数: 7558 | 12 呵呵，太谢谢了，回头试试。
根据
+
【在 G*******s 的大作中提到】
: 要是你的字符串'b1'中的'1'也是动态生成的，也是一样的。类似很多其他语言里的根据
: 变量名字符串做个宏替换得到真正的变量。
: pro test
: b1 = [1.,2.,3.]
: for j = 1, 1 do begin
: str_of_var = 'b' + strtrim(string(j),2)
: endfor
: for i = 0, n_elements(b1) -1 do begin
: r = execute ( 'b_tmp = ' + str_of_var + '[' + strtrim(string(i),2) +
: ']' )
| a*******r
发帖数: 7558 | 13 总结一下两种解决办法。感谢Geomatics和James Jones的详尽回复。
1. Use SCOPE_VARFETCH, which can be compiled in a Runtime program, if
necessary.
The syntax "myArray[i] = scope_varfetch('var')" will copy the value of a
variable named "var" that is
defined in the current scope (scope is where you are running in the current
"call stack" - what routine
call you are currently running in) into 'myArray'.
2. Use EXECUTE, which cannot be compiled in a .sav Runtime program:
EXECUTE treats its string argument as a command that |
|
