Fork me on GitHub
#beginners
<
2016-11-24
>
roelofw06:11:38

oke, one problem I do not see how to solve it

roelofw06:11:07

Let's say we have the seq [ 1 [ 2 3] 4]

roelofw06:11:24

We first have a 1 and that one can be conj with a acc

roelofw06:11:59

Then we have a seq [ 2 3 ] . We have to iterate trougth that one.

roelofw06:11:54

But how di I "save" the contents of the 4 . Do I need to use 3 variables acc , rest seq and the rest of the whole seq ?

seancorfield07:11:33

@roelofw Consider instead that you could concat sequences together -- so if you have a non-sequence element, you can turn it into a sequence by wrapping it in [ ], and if you do have a sequence you can recursively flatten it and then concat it (since it may contain nested sequences).

seancorfield07:11:17

Is this a 4clojure puzzle? Which one? (so I know exactly what problem you're trying to solve)

roelofw08:11:27

@seancorfield This is a 4clojure puzzle and here is the link : http://www.4clojure.com/problem/28

roelofw08:11:01

As described im not allowed to use flatten, otherwise the puzzle would be very simple

seancorfield08:11:32

Since you need to handle deeply nested sequences, you'll need to call your "flatten" function recursively on any vectors or lists but you can do this with mapcat and a function that does what I described above.

sb08:11:46

Hello, Could you help me - give an example/ tutorial - what is possible with clojure in the NLP area?

sb08:11:05

(eg. generate english communication from AI)

roelofw08:11:54

@seancorfield you mean the part , if it's not a seq turn it into a seq otherwise take all the elements out of it ?

seancorfield08:11:39

@sb: Google suggests this might be a good starting point for you https://github.com/dakrone/clojure-opennlp/blob/master/README.markdown

sb08:11:14

Yes, I see that. and the stanford nlp too

sb08:11:14

For me mainly the question, experience with that

sb08:11:22

what do you think about, what is possible

seancorfield08:11:27

@roelofw: if coll? x then recursively call your flatten on it else return [x] -- then your flatten function would just mapcat that logic over the collection. Make sense?

roelofw08:11:43

oke, that way

roelofw08:11:59

you almost give the code away

seancorfield08:11:22

@sb: I think your question is too vague. You can do anything with Clojure that you can do with Java libraries, just easier.

seancorfield08:11:55

@roelofw: I avoided parentheses so it's not code 😆

roelofw08:11:12

@seancorfield time to experiment with the code. But I was on the good way when I thought about mapcat

seancorfield08:11:26

:thumbsup::skin-tone-2:

sb08:11:36

@seancorfield Yes, I know. I saw a few really good example with java libraries (like stanford-nlp). I try a few.. and I will see. By the way thanks!

roelofw10:11:00

bummer, I see a object here :

(defn my-flatten [s] (mapcat (fn [_ n ]  (if (coll? n) (my-flatten n ) ([n])) s )))

(my-flatten [1 [2 3 ] 4]) 

roelofw11:11:10

anyone a tip where I go wrong ?

rauh11:11:16

@roelofw Indent your code properly and you'll probably see 1-2 mistakes

roelofw11:11:43

@rauh : You mean something like this :

(defn my-flatten [s] 
    (map (fn [_ n ]  
         (if (coll? n) 
           (my-flatten n ) 
           ([n]))
         s )))

genmeblog11:11:18

yes, line 5 as my first hint

roelofw11:11:35

you mean [x] where I want to convert a number to a vector ?

roelofw11:11:27

hmm, for me that is line 5

genmeblog11:11:42

there are more problems in the code

roelofw11:11:31

oke, what I try to do is take a item of a seq with map.

roelofw11:11:59

When that item n is not a seq then make it a seq

roelofw11:11:33

otherwise call the function again so it get flattened with mapcat

roelofw11:11:38

that was my idea

roelofw11:11:04

As a challenge I have to flatten a deep nested seq without using flatten

genmeblog11:11:08

I know, I see

genmeblog11:11:44

but first correct some mistakes

genmeblog11:11:11

first hint: there is a difference between a and (a)

roelofw12:11:14

you still refering to the ([n] ) part ?

roelofw12:11:31

Im still confused what you exactly wants

genmeblog12:11:47

I'm talking about difference between ([n]) vs [n]

roelofw12:11:04

So it can be [n] instead of ([n]) ?

genmeblog12:11:35

yes, question is: do you know why?

genmeblog12:11:42

because it's crucial

genmeblog12:11:41

your first solution (with mapcat) works after you correct 3 errors

genmeblog12:11:44

this is first one

roelofw12:11:54

I think ([x]) is a seq containing a vector

roelofw12:11:07

[x] is a vector with one element

genmeblog12:11:27

try to make in repl

genmeblog12:11:07

and see what it does or what errors you get

roelofw12:11:54

with the second you get this error : ArityException Wrong number of args (0) passed to: PersistentVector clojure.lang.AFn.throwArity (AFn.java:429)

roelofw12:11:26

first one works fine and also the thirth one

genmeblog12:11:29

yes, arity exceptions you get when you try to call function with wrong number of arguments

roelofw12:11:04

and the last one works also , gives as output 1

roelofw12:11:23

I know that after a ( clojure expects a function

genmeblog12:11:30

yes, exactly!

genmeblog12:11:47

and that's why ([x]) doesn't produce sequence

roelofw12:11:49

except when doing a quote , then you tell clojure to handle it as it is

genmeblog12:11:24

not exactly, '(a b c) produces list

roelofw12:11:40

I think I need to use (seg [x] )

genmeblog12:11:41

(type '(1 2 ));; => clojure.lang.PersistentList

genmeblog12:11:18

why? [x] is already a sequence

roelofw12:11:03

so one error is solved 🙂

genmeblog12:11:27

ooops, no it isn't, sorry

genmeblog12:11:39

but it doesn't matter

genmeblog12:11:46

mapcat works on vectors too

roelofw12:11:06

oke, time for error 2

roelofw12:11:40

any tip where I can find it

roelofw12:11:58

You said there are still 2 errors but I cannot see it

genmeblog12:11:26

yes, first one is parenthesis

genmeblog12:11:49

I meant second one

rauh12:11:49

@roelofw you never indented your code properly. Use Cursive's help if you can. It'll indent itproperly

genmeblog12:11:19

third one you get when you call after fixing two first bugs

roelofw12:11:00

@rauh : I use the intendation og cursive all the time 😞

genmeblog12:11:20

ok, then see how many arguments you have for each function and check closing paranthesis

genmeblog12:11:43

*parantheses

roelofw12:11:54

flatten has one. only the given s

roelofw12:11:27

map has only 1 , the current item named n

roelofw12:11:13

the if then works also on n

roelofw12:11:02

aha. the s is on the wrong place. its looks now if it's a part of the anymous function

genmeblog12:11:18

map needs two parameters, function and collection

roelofw12:11:01

oke, it has now . the anymous function and s

genmeblog12:11:07

if needs three parameters: predicate, value for true and value for false

roelofw12:11:22

oke, I have now this :

(defn my-flatten [s]
  (map (fn [_ n ]
         (if (coll? n)
           (my-flatten n )
           [n]))
         s )) 

roelofw12:11:43

and I now see a arity error on my-flatten

genmeblog12:11:59

actually not in my-flatten

roelofw12:11:27

I see this error : ArityException Wrong number of args (1) passed to: core/my-flatten/fn--1463 clojure.lang.AFn.throwArity (AFn.java:429)

genmeblog12:11:41

fn--1463 is a key

roelofw12:11:53

Which is wierd, my flatten has and must have 1 argument

genmeblog12:11:33

fn--1463 ss internal anonymous function, and error says that it's called with one (which is wrong) argument

roelofw12:11:14

my-flatten has 1 argument on first calling nl. s

genmeblog12:11:25

it's not about my-flatten

roelofw12:11:43

map has also 1 argument the current item

genmeblog12:11:46

it's about my-flatten/fn--1463

roelofw12:11:10

oke, but i cannot see what that function is

genmeblog12:11:30

you have only one anonymous function inside your my-flatten

genmeblog12:11:36

so this is this one

roelofw12:11:59

That one has only 1 argument. namely n

genmeblog12:11:16

you're wrong

roelofw12:11:24

the other is _ . so it is not important

genmeblog12:11:49

but it is treated as argument

roelofw12:11:18

oke, so at first it has 2 arguments , one who is not important and the n \

roelofw12:11:47

I check the if then with n , which looks right to me

genmeblog12:11:58

"In Clojure, the underscore is used idiomatically to indicate that the argument it identifies is not subsequently used."

genmeblog12:11:30

map expects a function which has exactly one argument

genmeblog12:11:38

you've provided function with two

roelofw12:11:48

then if n is a seq , I called my_flatten again with n otherwise I put n in a vector

roelofw12:11:13

oke, then I confused map with reduce

genmeblog12:11:47

underscore _ is valid argument name

roelofw12:11:55

oke, now n is not known

genmeblog12:11:56

(defn underscore [_] _)
works well

roelofw12:11:14

I have to find another way to use the current item 😞

genmeblog12:11:27

(underscore "aaa") ;; => "aaa"

genmeblog12:11:39

show me what you have

roelofw12:11:35

got it working, Some code were overwritten

roelofw12:11:46

This one :

(defn my-flatten [s]
  (mapcat  (fn [ n ]
         (if (coll? n)
           (my-flatten n )
           [n]))
         s ))


(my-flatten [1 [2 3 ] 4])

roelofw12:11:56

works with my own example

genmeblog12:11:11

with mine as well

roelofw12:11:11

Now I hopes it works also with the examples of 4 clojure

genmeblog12:11:41

(my-flatten [1 [22 [:e] '(1 2 3 [33 33 {:e a}]) 33] [33 33]])
;; => (1 22 :e 1 2 3 33 33 :e a 33 33 33)

roelofw12:11:43

@tsulej thanks for the help and patience with me

genmeblog12:11:59

you're welcome 🙂

genmeblog12:11:01

one more hint

roelofw12:11:37

always appericaited

roelofw12:11:49

and time for a late lunch

genmeblog12:11:53

(defn my-flatten [xs]
  (mapcat 
   #(if (coll? %)
      (my-flatten %)
      [%])
   xs))

genmeblog12:11:18

#() instead of (fn ...)

roelofw12:11:22

aha, instead of fn use the # syntax

genmeblog12:11:26

just a syntactic sugar

roelofw12:11:44

I have to dig into the # , Im still used to use fn

roelofw13:11:10

tsulej did you ever work with haskell. I know they use xs for a list/vector

genmeblog13:11:13

no, I was trying to learn it once but I gave up

genmeblog13:11:34

this is in use in Scala too (xs is plural for 'x')

roelofw13:11:47

oke, thanks

mikecarter13:11:39

i'm trying to copy a file to a resource path that's different in development than it is to in production, any ideas?

mikecarter13:11:56

is there a way to get the current resource path?

mikecarter13:11:32

usually io/resource takes care of it, but it doesn't work for a file that doesn't exist yet

dpsutton13:11:41

This has bitten me before. It seems like the resource directory is not present in production

dpsutton13:11:50

I'm interested in this answer

dpsutton13:11:55

I think this is a jvm question

mikecarter13:11:02

it is present, but it's within the jar

mikecarter13:11:18

so i have a resources directory alongside the jar in production

mikecarter13:11:24

but in development, it's called dev-resources

mikecarter13:11:26

any ideas would be great!

mikecarter14:11:03

@dpsutton I think i've got it

mikecarter14:11:29

instead of calling io/resource on the none-existent file, i'm doing it on the target directory then amending the new filename

mikecarter14:11:37

let me know if you want to discuss it further!

roelofw16:11:46

Can I somehow flatten a list 1 level. so (( [ 1,2] )) will be ( [ 1,2] ) ?

roelofw16:11:03

I cannot find the right method

kauko16:11:53

apply concat

roelofw16:11:26

@kauko thanks

agile_geek16:11:43

@roelofw of course if you know that you're upper level list will only have one item (or at least you're only interested in the first) you can simply use (first xs) where xs is your list

roelofw17:11:11

I know. I had to repeat a item several times in a seq so (1 2 ) 3 would be ( 1 1 1 2 2 2 3 3 3 )