I tend to not worry too much about it. I use clj-kondo's static analysis to tell me when something doesn't exist (if I've renamed a function, for example) and I tend to use let more than def in a rich comment block, so I don't end up polluting the namespace all that much.

removing vars from one namespace (with ns-unmap) and removing an ns and re-loading (with ns-remove followed by require) are relatively low wieght there is also clojure.tools.refresh that actually removes all your namespaces and reload them (meant for automated editor usage), this led to the creation of stuartsierra/system for automatically recreating initial application state (when you have resources that need initializing during repl development, like db connections)

Calva’s debugger won’t let you step into Java land. I think only Cursive might offer something like that.

Many thx for the pointer!

(so; I guess be careful with x containing false or nil, but I’d assumed from your example we are dealing with numbers here)

basically I have data like [[820540800000 #inst "1996-01-02T00:00:00.000-00:00" 13 13 12.375] [820627200000 #inst "1996-01-03T00:00:00.000-00:00" 12.3334 12.6666 11.9166] [820713600000 #inst "1996-01-04T00:00:00.000-00:00" 11.875 11.9584 10.9584] [820800000000 #inst "1996-01-05T00:00:00.000-00:00" 11.0416 11.25 10.7916] [821059200000 #inst "1996-01-08T00:00:00.000-00:00" 11.2084 11.25 11]] and I want to extract the vector only which contains 820540800000 and 820800000000 (selective filtering)

(filter (comp (set x) first) items) should then suffice

That works thank you so much

Filtering via sets is one of those Clojure idioms that other languages don’t have and that you find amazingly useful once you grok it.

brother I implemented that

but what I wanted to do is much complex than it

I have matrix something like this `[["19996/28/11" 13 13 12.375] ["1997/28/11" 12.3334 12.6666 11.9166] ["1998/27/11" 11.875 11.9584 10.9584] ["1999/28/11" 11.0416 11.25 10.7916] ["2000/28/11" 11.2084 11.25 11]]` and dates of 11/28 like `["19996/28/11" "19997/28/11" "19998/28/11" "19999/28/11" "2000/28/11" ]` what I want to do if data of 11/28 is found just return the data, but if the data of 11/28 isn't found in the matrix return the data 11/27

this is what I really want to do

Then you need to dump the data into an array, sort it, and use something like binary search. If you don’t find the item at the end, then back up one item and return that.

BTW, that has nothing to do with Clojure. That’s just basic algorithms.

@U02RRUT1ALQ Hi, it's hard to see what's going on in that picture. If you are able to use Slack from the computer where you are seeing this error, could you please copy-paste the text of the stacktrace in your Slack message? Also, please describe what you are trying to do. Maybe it's obvious to some from the stack-trace, but other beginners in the channel will benefit from knowing the proper context.

https://support.microsoft.com/en-us/windows/use-snipping-tool-to-capture-screenshots-00246869-1843-655f-f220-97299b865f6b

what have you tried so far?

and also what should be the result for the matrix in your example?

I have tried this

sharing you the code snippets

Btw your example only contains dates that are 27/11 or 28/11 so it might not be a good case

it contains many dates

every date from 1970-2021

to keep the code clean I just shared the snippet, the case is I wanted to extract the vector containing data of 11/28 if data for 11/28 is not found then return the data of 11/27

(def dates ["19996/28/11" "19997/28/11" "19998/28/11" "19999/28/11" "2000/28/11" ])

(for [x data :when (some #(first x) dates)] x)

I was trying this for loop but it is only returning the data for 11/28 when data of 11/28 is not available I wanted to get data of 11/27

Oh, so 1996/28/11 is in the original data so the code has to return that entry but 1998/28/11 is not in the original data so the code should return the entry for 1998/27/11? (btw you have some extra 9s there)

you need to use a library to parse the string into an actual date

we have a matrix which contains data of every date from 1996-01-01 to 2021-12-21 and I wanted to extract data of 11/28 for every year like data for 1996-11-28 , 1997-11-28 upto 2021-11-28 but for some years (for example 2004/11/28) data is not available in that case I want data for 2004/11/27

I am using the actual date using (js/Date. date) I am using the string here for simplicity

I see. That changes the problem statement quite a bit, don't you think? https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/setDate Or you could consider using a https://github.com/henryw374/cljc.java-time (it has functions like minus-days and plus-days)

I know how dates manipulated using higher level libraries, it is basically an iteration problem I have a data and a vector of dates . I want to basically match matrix with vector, if the data is found for 11/28, return it, if not found return the data for 11/27

First of all, "iteration" is doing a single thing many times, so the best thing you can do is reduce the problem to a single item. Solve the problem for a single date and then map the function you wrote over the vector of dates

I put this into another thread, but you should: sort the dates, then binary search the resulting array/vector. If you find the date you want, great. If not, at the last index of your binary search, go backwards one item and that should be what you want. And this has nothing to do with Clojure. It would be the same algorithm in any language. If your array is really short, then just sort it in reverse and linearly search it until you either find the item or a value less than the item you’re looking for.

Another way to do this is to put the data into a map with the date as the key. Look up the key in the map. If you find it, great, return the data. If not, decrement the date by one and search for that. If you find it, great. If not, decrement the date by one and search for that. And so on. In that case, you’d probably want to covert all the dates to java.time/LocalDate so the date math was easy.

Map approach looks fine to me this is what I want to be precise and as I mentioned I am using java Dates

The map approach assumes that any gaps between dates are small. It’s effectively a fast initial search using the map, followed by a slow linear search if you don’t find the initial date. If there are lots of large gaps, then you should use the binary search. But if this is something like financial trade data, where you’re just jumping over weekends and holidays, but otherwise every M-F is a trading day, then the map approach will work well.

most of the gap is small like one day or two day

and yes it is financial trade data

your advice just made my day thank you so much brother

{ "errors": [ { "message": "Exception in resolver for `Query/flightLine': Wrong number of args (3) passed to: neptune-browser-graphql-service.schema/resolver-map/fn--6216", "extensions": { "field-name": "Query/flightLine", "arguments": { "date": "20210909", "flightNumber": 1111 }, "location": { "line": 4, "column": 2 }, "path": [ "flightLine" ] } } ] }

can your anonymous functions all take & args and sort it out within the function?

then you can call it with whatever number of args and it's fine

it's a hack, and not ideal, but it's a thing that might work

it has been a while, but I believe lacina always passes the same number of args

always 3

the context, the arguements map, the value (those might have different names in the docs, I forget)

https://lacinia.readthedocs.io/en/latest/resolve/overview.html#field-resolver-arguments

Thanks!

I was able to solve this, thanks for the help!

my resolver function was expecting the wrong number of params

and then I had to restart emacs/cider

@USDPTD3FY another trick for debugging something like this is to make an argument inspecting version of your function:

(ins)user=> (defn debug-args
              [f]
              (fn [& args]
                (println "arguments to function" f "--" (pr-str args))
                (apply f args)))
#'user/debug-args
(ins)user=> (def str2 (debug-args str))
#'user/str2
(ins)user=> (str2 "a" :b 'c \d)
arguments to function #object[clojure.core$str 0x6a84bc2a clojure.core$str@6a84bc2a] -- ("a" :b c \d)
"a:bcd"

Thanks this is a great idea

it's easy to extend this to inspecting return values too, of course - such a simple thing to implement