Look for "A" value in list

[DRossger]

Hello all!

I have a list, looks like this

(("S" 152747.0 6.4086e+006 72.3828 "A" -4.19779) ("S" 152752.0 6.4086e+006 72.3091 "A" -1.95332) ("S" 152770.0 6.40863e+006 72.1742 "A" 0.722905) ("S" 152774.0 6.40863e+006 72.1143 "A" -2.4611) ("S" 152786.0 6.40866e+006 71.9021 "A" 9.32426))

and I want have all value from "A" ... ("A" -4.19779) ("A" -1.95332) ("A" 0.722905)....

I was thinking and try it with lambda expressions but whtat is wrong?

((lambda (x)
   (while
     (not
       (member "A" (nth (1- (length area_list)) area_list))
     )
   )
  )
 (princ x)
 )  

[martti.halminen · Accepted solution]

---

@DRossger wrote:

Hello all!

I have a list, looks like this

(("S" 152747.0 6.4086e+006 72.3828 "A" -4.19779) ("S" 152752.0 6.4086e+006 72.3091 "A" -1.95332) ("S" 152770.0 6.40863e+006 72.1742 "A" 0.722905) ("S" 152774.0 6.40863e+006 72.1143 "A" -2.4611) ("S" 152786.0 6.40866e+006 71.9021 "A" 9.32426))

and I want have all value from "A" ... ("A" -4.19779) ("A" -1.95332) ("A" 0.722905)....

---

Assuming your list is assigned into the variable data, and you want to have everything in the list after "A":

(mapcar '(lambda (x) (member "A" x)) data)

=> (("A" -4.19779) ("A" -1.95332) ("A" 0.722905) ("A" -2.4611) ("A" 9.32426))

--

--

[DRossger]

Thanks a lot that was the answer I want have...

second questions:

If I program with lambda, there is a control what can be inside (x) ? I have not much expierence with lambda, how I can check as function works rigtht ?

[pbejse · Accepted solution]

---

@DRossger wrote:

Thanks a lot that was the answer I want have...

second questions:

If I program with lambda, there is a control what can be inside (x) ? I have not much expierence with lambda, how I can check as function works rigtht ?

---

by using the expression on the first item of the list argument

(mapcar '(lambda (x) (member "A" x)) data)

(setq x (car data))<--- 

("S" 152747.0 6.4086e+006 72.3828 "A" -4.19779) 

(member "A" x)<--- 

("A" -4.19779)

and on every subsequent item on the list 

[DRossger]

Thanks for explanantion, it´s clear now