I want to achieve this
if a?
switch a
'hello'
else 'hi'
How to chain an if statement with switch statement if the condition isn't null or undefined?
As far as I can tell, your switch syntax is wrong. Something like that might be what you are looking for:
f = (a) ->
if a?
switch a
when 'bonjour'
'hello'
else
'yo'
else
'hi'
console.log f null
console.log f 'bonjour'
console.log f 'guten tag'
Producing:
sh$ coffee t.coffee
hi
hello
yo
Please note you can have an else close both for the switch statement (where it denotes the default case) and for the if statement.
Depending your needs, you might want to write the other way around:
f = (a) ->
switch a
when 'bonjour'
'hello'
else
if a? then 'yo' else 'hi'
Or even get completely rid of the if:
f = (a) ->
switch a
when 'bonjour'
'hello'
when null, undefined
'hi'
else
'yo'
That works. I found out that I have an spacing error.
Related
In SQL Server, is there a way for nested case statements to ELSE continue the nesting CASE statement?
CASE
WHEN ... then
CASE
WHEN ... THEN
ELSE **[Continue to below WHEN]** END
WHEN ... then
WHEN ... then
ELSE ... END
Wondering if I can keep the code clean by not copy/pasting the proceeding WHEN statements into the nested CASE.
Flatten the nesting. So instead of this:
CASE
WHEN A then
CASE
WHEN B THEN C
WHEN D THEN E
ELSE **[Continue to below WHEN]** END
WHEN F then G
WHEN H then I
ELSE J END
You have this:
CASE
WHEN A AND B THEN C
WHEN A AND D THEN E
WHEN F then G
WHEN H then I
ELSE J END
A CASE expression (not statement: CASE cannot branch among SQL segments, only return a value) will stop at the first match, so by flattening the nesting and using and AND to tie in the nested conditions you will get the desired behavior.
I am not sure if we can use if else in Hiveql or not. So wanted to know how we can write if else statements in hiveql
You can use IF (Returns valueTrue when testCondition is true, returns valueFalseOrNull otherwise):
if(boolean testCondition, T valueTrue, T valueFalseOrNull)
Or CASE (When a = true, returns b; when c = true, returns d; else returns e):
CASE WHEN a THEN b WHEN c THEN d ELSE e END
Or any other supported conditional function.
I have the following if else statement that created by myself in order to link to the if else statement given in second part:
m=4
if m==3
disp(true)
else
disp(false)
Second part ( this code is fix cannot be change):
if (true)
A=Hello World
else
A=Bye
If using the first part code, my output will be
A=Hello World
but my desire output is
A=Bye
Anyone one have idea to edit the first part, because now my return value in first part not able to link to my second part.
If you can't change the second part's code, I'm afraid your desire cannot be fulfilled. Or rather, I'm afraid your code won't run at all, because your perenthesis, quotes, end-statement (and arguably semicolons) are not in place.
if true
A = 'Hello World';
else
A = 'Bye';
end
This code will return A = 'Hello World', no matter what, since true is always true. If-else conditions work like this:
if (*what's in here evealuates to true*)
%do stuff
else (*if what's up there does not evaluate to true*)
%do other stuff
Clearly, true will always evaluate to true. So the above if-else condition will always return A = 'Hello World'.
You don't need two if statements in order to accomplish this task. One is more than enough to perform all what you need:
m = 4;
if (m == 3)
A = 'Hello World';
else
A = 'Bye';
end
disp(A);
A few comments concerning your code:
if statements need to be closed with an end
if (true) will always pass into the statement
the disp function doesn't assign a value, its only goal is to display it in the Command Window
in order to work with text, you have to enclose it within single quotes ' (char array) or double quotes " (string), more info here
If you posted only small excerpts of your code and you need to perform those two checks sequentially, in different parts of your script, then:
m = 4;
if (m == 3)
m_equals_3 = true;
disp('M == 3');
else
m_equals_3 = false;
disp('M ~= 3');
end
% then, somewhere else...
if (m_equals_3)
A = 'Hello World';
else
A = 'Bye';
end
% ...
I guess this is a homework exercise. You should disclose that if it’s the case.
The exercise requieres you to change the workspace such that the second bit of code evaluated the else case. This can be accomplished by changing the meaning of true. In your first bit of code, make it so that
true = flase;
Or equivalently,
true = 0;
Note that this is really bad form, if you ever do something like this outside of a homework exercise that explicitly asks you to do so, you’ll get fired or maybe even shot. You’ve been warned!
By the way, I assume that the missing quote characters around the strings and the missing ends are typos?
I'm trying to implement the logic in Cypher where, based on a particular condition (CASE Statement), I would create some nodes and relationships; the code is as below
MATCH (g:Game)-[:PLAYER]->(u:User)-[r1:AT]->(b1:Block)-[:NEXT]->(b2:Block)
WHERE g.game_id='G222' and u.email_id = 'xyz#example.com' and b1.block_id='16'
SET r1.status='Skipped', r1.enddate=20141225
WITH u, b2,b1, g, r1
SET b1.test = CASE b2.fork
WHEN 'y' THEN
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2 {fork:'fail'}) RETURN 1
ELSE
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2) RETURN 2
END
WITH u, g
MATCH (u)-[:TIME]->(h:Time)<-[:TIME]-(g)
SET h.after = 0
SET h.before = h.before + 1
In this query there is a merge statement within the WHEN 'y' THEN, this query throws an error:
Invalid input ']': expected whitespace or a relationship pattern (line 7, column 82)
"MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2 {fork:'fail'}) RETURN 1"
Basically I'm trying to create a relationship based on a property i.e. a MERGE within a CASE statement, I tried different ways to get this working like doing a return so that case when returns some value etc. but nothing worked so far.
What could be the issue with this query?
To do conditional write operations you need to use the FOREACH trick. Using CASE you either return a one element array or a empty one. FOREACH iterates over the CASE expression and therefore conditionally executes the action. If you want an ELSE part as well you need to have a another FOREACH using the inverse condition in the CASE. As an example, instead of
WHEN 'y' THEN
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2 {fork:'fail'}) RETURN 1
ELSE
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2) RETURN 2
END
use
FOREACH(ignoreMe IN CASE WHEN 'y' THEN [1] ELSE [] END |
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2 {fork:'fail'})
)
FOREACH(ignoreMe IN CASE WHEN NOT 'y' THEN [1] ELSE [] END |
MERGE (u)-[r2:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2)
)
See also Mark's blog post on this.
Fixed the issue as below
WITH u, b2,b1, g, r1, CASE WHEN (b1.fork='y' and b2.fork='success') or (b1.fork='n') or (b1.fork='success') THEN ['ok'] ELSE [] END as array1
FOREACH (el1 in array1 | MERGE (u)-[r2:STAGE {startdate:20141225, enddate:99999999, status:'InProgress'}]->(b2))
i.e. used CASE WHEN to create a dummy array that in a way has dummy elements matching the count of matches and then use FOREACH to iterate through the result.
Again, thanks Stefan for the idea...
Deepesh
The APOC plugin supports Conditional Cypher Execution, which now allows us to avoid the FOREACH workaround.
For example, you can do this:
MATCH (g:Game)-[:PLAYER]->(u:User)-[r1:AT]->(b1:Block)-[:NEXT]->(b2:Block)
WHERE g.game_id='G222' AND u.email_id = 'xyz#example.com' AND b1.block_id='16'
SET r1.status='Skipped', r1.enddate=20141225
WITH u, b2, g
CALL apoc.do.when(
b2.fork = 'y',
"MERGE (u)-[:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2 {fork:'fail'})",
"MERGE (u)-[:STAGE {startdate:20141225, enddate:'99999999', status:'InProgress'}]->(b2)",
{u: u, b2: b2}) YIELD value
WITH u, g
MATCH (u)-[:TIME]->(h:Time)<-[:TIME]-(g)
SET h.after = 0
SET h.before = h.before + 1
Although this answer does help me, I found the syntax very hard to understand. So that's why I wrote my own answer. Here I read a tsv file and generate multiple types of edges.
LOAD CSV WITH HEADERS FROM 'file:///data.tsv' AS r FIELDTERMINATOR '\t'
WITH r.movie_id as movie_id, r.person_id as person_id, r.category as category
MATCH (p:Person {person_id:person_id})
MATCH (m:Movie {movie_id:movie_id})
FOREACH (_ IN CASE WHEN category='actress' THEN [1] ELSE [] END |
MERGE (p)-[:ACTRESS {}]->(m)
)
FOREACH (_ IN CASE WHEN category='director' THEN [1] ELSE [] END |
MERGE (p)-[:DIRECTOR {}]->(m)
)
FOREACH (_ IN CASE WHEN category='cinematographer' THEN [1] ELSE [] END |
MERGE (p)-[:CINEMATOGRAPHER {}]->(m)
)
FOREACH (_ IN CASE WHEN category='actor' THEN [1] ELSE [] END |
MERGE (p)-[:ACTOR {}]->(m)
)
Here _ is some variable which is simply not used anywhere but a necessity for the syntax of cypher
I am fresh on SML and doing a homework by that. "Write a function number_in_month that takes a list of dates and a month (i.e., an int) and returns how many dates in the list are in the given month."
That's what I worked out and cannot see anything wrong with it. Please help.
`
fun number_in_month (dates: (int*int*int) list,month:int) =
if ((#2 (hd dates)) = month)
then val flag=1 flag+number_in_month(tl dates, month)
else number_in_month((tl dates),month)`
REPL tells that: replacing VAL with EQUALOP.
You can't bind variables "that way". A binding of a variable is a declaration and thus cannot be done where an expression is expected.
In this case you have to use a let-in-end expression
fun foo x =
let
val a = 42
in
a*x
end
Your problem is endless recursion. Compiler can't get out of it because independ of result if..then..else you're running your function again
Try this:
fun number_in_month (dates: (int*int*int) list,month:int) =
if null dates
then 0
else if ((#2 (hd dates)) = month)
then val flag=1 flag+number_in_month(tl dates, month)
else number_in_month((tl dates),month)
I tried to fix it by myself and that was my solution:
fun number_in_month (dias: (int*int*int) list,mes:int) =
if null dias
then 0
else if ((#2 (hd dias)) = mes)
then let val flag = 1 + number_in_month(tl dias, mes)
in flag
end
else number_in_month((tl dias),mes)
I hope you can also use it!
The error message from REPL is confusing, but Jesper is right that you should use let-in-end expression, if you need assignment statement in functions. That will surely get you that error resolved.