I want to create a function that gets the first value of a table field if two other field values match the two given function parameters.
I thought this would be easy. But I found nothing in the internet or M documentation that could solve this.
I don't know if I have to loop through a record or if there is a top level function.
= (val1 as text, val2 as text) as text =>
let
result = if [Field1] = val1 and [Field2] = val2 then [Field3] else ""
in
result
As far as I understand your wish, table and column names are hard coded (i.e. you intend to apply the function only for specific table). Then you may use following approach:
// table
let
t1 = #table({"Field1"}, List.Zip({{"a".."e"}})),
t2 = #table({"Field2"}, List.Zip({{"α".."ε"}})),
join = Table.Join(t1&t1,{}, t2&t2,{}),
add = Table.AddIndexColumn(join, "Field3", 0, 1)
in
add
// func
(val1 as text, val2 as text) => Table.SelectRows(table, each [Field1] = val1 and [Field2] = val2)[Field3]{0}
// result
func("d","β") //31
Related
here is the sql statement I am trying to translate in jpa :
select
id,
act_invalidation_id,
last_modification_date,
title,
case when act_invalidation_id is null then 1 else 0 end as test
from act order by test, last_modification_date desc
The actual translation
Root<Act> act = query.from(Act.class);
builder.selectCase()
.when(builder.isNull(actRoot.get("actInvalidation")), 1)
.otherwise(0).as(Integer.class);
Expression<?> actInvalidationPath = actRoot.get("actInvalidation");
Order byInvalidationOrder = builder.asc(actInvalidationPath);
Path<Date> publicationDate = actRoot.get("metadata").get("publicationDate");
Order byLastModificationDate = builder.desc(publicationDate);
query.select(act).orderBy(byInvalidationOrder, byLastModificationDate);
entityManager.createQuery(query).getResultList();
I try to create a temporary column (named test) of Integer type and orderby this column, then orderby lastmodificationdate. The content of this new column is determined by the value of actInvalidation field.
In short: How to create a temp column with integer values, then order by this temp column in jpa ?
Thank you
I didn't test this but it should work like this:
Root<Act> act = query.from(Act.class);
Expression<?> test = builder.selectCase()
.when(builder.isNull(actRoot.get("actInvalidation")), 1)
.otherwise(0).as(Integer.class);
Expression<?> actInvalidationPath = actRoot.get("actInvalidation");
Order byInvalidationOrder = builder.asc(actInvalidationPath);
Path<Date> publicationDate = actRoot.get("metadata").get("publicationDate");
Order byLastModificationDate = builder.desc(publicationDate);
Order byTest = builder.asc(test);
query.select(act).orderBy(byTest, byInvalidationOrder, byLastModificationDate);
entityManager.createQuery(query).getResultList();
I have a question about the way I put together this piece of Lua code.
Say, there is a function like the one below, containing 200 myTable tables, where the names are ordered alphabetically:
function loadTable(x)
local myTable
if x == "aaron" then myTable = {1,2,3,4,5,6,7,8,9,0}
elseif x == "bobby" then myTable = {1,3,3,4,5,8,7,8,9,1}
elseif x == "cory" then myTable = {1,2,3,3,3,6,7,8,9,2}
elseif x == "devin" then myTable = {1,2,3,4,5,2,3,4,9,0}
...
else
print("table not available")
end
return myTable
end
and now I want to find the table corresponding to x == "zac" (which happens to be somewhere at the end). I use this line of code:
local foundTable = loadTable("zac")
Isnt this like not efficient at all? If it has to find the table at the very end of the function it has to go through all the previous lines of code. Is there some way to code this more efficiently in lua and find the correct table faster? ?
This can become a lot faster by using... a table!
Simply make a table whose keys are the name of the person and the values are the table you want to load, like this:
local tables = {
john = {1,2,3,4,5,6,7,8,9,0},
peter = {1,3,3,4,5,8,7,8,9,1},
william = {1,2,3,3,3,6,7,8,9,2},
victoria = {1,2,3,4,5,2,3,4,9,0}
--...
}
Then, instead of calling loadTable("richard") simply use tables["richard"] or tables.richard if the key is a valid identifier
I have four parameters to my function a dataset, array consisting of expressions (aggregate functions), array consisting of column names on which to apply expressions and an array consisting of columns on which I have to group by.
My problem is how can I handle dynamic columns or fields for expression and group by as it can vary in numbers (depends on array values).
I have written code for static query, but need a generic way...
This is my code:
public void ExpressionManipulation(DataSet dsExprEvaluate, string[] strExpressions, string[] colName, string[] groupbyFields)
{
int groupByLength = groupbyFields.Length;
var groupByQueryEvaluate = from table in dsExprEvaluate.AsEnumerable()
group table by new { column1 = table["DataSourceType"], column2 = table["Polarity"] }
into groupedTable
select new
{
x = groupedTable.Key, // Each Key contains column1 and column2
y = groupedTable.Count(),
//z = groupedTable.Max(column1),
z = groupedTable.Sum(table => Convert.ToInt32(table["Polarity"]))
};
}
Like in above I can have n number of fields in group by like for now I have taken only two (DataSourceType and Polarity) and similar I can have n number of fields for expressions, for sum, count etc which will be as an array as parameter.
Please help me through this, it is driving me crazy.
Thanks in advance.
I figured it out myself and the solution i ended up is with:
var objGroupSumCountkey = dt.AsEnumerable()
.AsQueryable()
.GroupBy("new ( it[\"DataSourceType\"] as GroupByColumnName1,it[\"Polarity\"] as GroupByColumnName2)", "it")
.Select("new ( Sum(Convert.ToDouble(it[\"Polarity\"].ToString())) as SumValue,Count() as TotalCount,it.key)");
in the above query all the parameters will be supplied as string, in Group By and select
I m trying to select a column's value from a datatable based on conditions.
var results = from DataRow myRow in dtCallBack.AsEnumerable()
where myRow.Field<DateTime>(1) == startDateTime
&& myRow.Field<int>(0) == callBackID
select myRow.Field<int>(3);
My datatable contains 4 columns ID,Date1,Date2,IntVal
I want to convert the variable results to int. (I want to return the column 4 IntVal)
var results = (from DataRow myRow in dtCallBack.AsEnumerable
where myRow.Field<DateTime>(1) == startDateTime
&& myRow.Field<int>(0) == callBackID
select myRow.Field<int>(3)).SingleOrDefault();
Well you've currently got an IEnumerable<int> by the looks of it. So which of those results do you want? What do you want to happen if there aren't any results?
If you're confident there's only a single result, you can use:
var result = results.Single();
If you want the first result or 0 if there aren't any, you could use
var result = results.FirstOrDefault();
If you want the first result and an exception if there aren't any, you could use
var result = results.First();
Basically there are lots of options, and you'll need to clarify your requirements before we can really give you a more concrete answer.
I have a table that is filled with random content that a user enters. I want my users to be able to rapidly search through this table, and one way of facilitating their search is by sorting the table alphabetically. Originally, the table looked something like this:
myTable = {
Zebra = "black and white",
Apple = "I love them!",
Coin = "25cents"
}
I was able to implement a pairsByKeys() function which allowed me to output the tables contents in alphabetical order, but not to store them that way. Because of the way the searching is setup, the table itself needs to be in alphabetical order.
function pairsByKeys (t, f)
local a = {}
for n in pairs(t) do
table.insert(a, n)
end
table.sort(a, f)
local i = 0 -- iterator variable
local iter = function () -- iterator function
i = i + 1
if a[i] == nil then
return nil
else
return a[i], t[a[i]]
end
end
return iter
end
After a time I came to understand (perhaps incorrectly - you tell me) that non-numerically indexed tables cannot be sorted alphabetically. So then I started thinking of ways around that - one way I thought of is sorting the table and then putting each value into a numerically indexed array, something like below:
myTable = {
[1] = { Apple = "I love them!" },
[2] = { Coin = "25cents" },
[3] = { Zebra = "black and white" },
}
In principle, I feel this should work, but for some reason I am having difficulty with it. My table does not appear to be sorting. Here is the function I use, with the above function, to sort the table:
SortFunc = function ()
local newtbl = {}
local t = {}
for title,value in pairsByKeys(myTable) do
newtbl[title] = value
tinsert(t,newtbl[title])
end
myTable = t
end
myTable still does not end up being sorted. Why?
Lua's table can be hybrid. For numerical keys, starting at 1, it uses a vector and for other keys it uses a hash.
For example, {1="foo", 2="bar", 4="hey", my="name"}
1 & 2, will be placed in a vector, 4 & my will be placed in a hashtable. 4 broke the sequence and that's the reason for including it into the hashtable.
For information on how to sort Lua's table take a look here: 19.3 - Sort
Your new table needs consecutive integer keys and needs values themselves to be tables. So you want something on this order:
SortFunc = function (myTable)
local t = {}
for title,value in pairsByKeys(myTable) do
table.insert(t, { title = title, value = value })
end
myTable = t
return myTable
end
This assumes that pairsByKeys does what I think it does...