To me, adding "Dump" to the end of an expression doesn't seem to do anything different, at least for seeing rows in a table. Can you point me to an example of where it is handy?
If you are just working with an expression, there is no reason to call Dump—it's called automatically. But, in the language selection box, LINQPad allows allows the selection of Statements and Program. Once you select one of those, you don't get any Dump output unless you call it.
With Statements or Programs, you might want to call Dump on multiple times. In those cases, it is handy to pass the Description parameters so you can distinguish the output.
There are also other parameters you can use to shape the output, such as depth, which limits the substructure details.
Simple example (Language=C# Statements):
var integers = Enumerable.Range(1,10);
integers.Select(i => new { i, v = i * i}).Dump("Squares");
integers.Select(i => new { i, v = i * i * i}).Dump("Cubes");
var output = "λ is awesome";
Encoding.UTF8.GetBytes(output)
.Dump("UTF-8");
Encoding.GetEncoding("Windows-1252").GetBytes(output)
.Dump("Windows-1252 (lossy)");
Related
I am trying to write a code which calculates the HCF of two numbers but I am either getting a error or an empty list as my answer
I was expecting the HCF, My idea was to get the factors of the 2 given numbers and then find the common amongst them then take the max out of that
For future reference, do not attach screenshots. Instead, copy your code and put it into a code block because stack overflow supports code blocks. To start a code block, write three tildes like ``` and to end it write three more tildes to close. If you add a language name like python, or javascript after the first three tildes, syntax highlighting will be enabled. I would also create a more descriptive title that more accurately describes the problem at hand. It would look like so:
Title: How to print from 1-99 in python?
for i in range(1,100):
print(i)
To answer your question, it seems that your HCF list is empty, and the python max function expects the argument to the function to not to be empty (the 'arg' is the HCF list). From inspection of your code, this is because the two if conditions that need to be satisfied before anything is added to HCF is never satisfied.
So it could be that hcf2[x] is not in hcf and hcf[x] is not in hcf[x] 2.
What I would do is extract the logic for the finding of the factors of each number to a function, then use built in python functions to find the common elements between the lists. Like so:
num1 = int(input("Num 1:")) # inputs
num2 = int(input("Num 2:")) # inputs
numberOneFactors = []
numberTwoFactors = []
commonFactors = []
# defining a function that finds the factors and returns it as a list
def findFactors(number):
temp = []
for i in range(1, number+1):
if number%i==0:
temp.append(i)
return temp
numberOneFactors = findFactors(num1) # populating factors 1 list
numberTwoFactors = findFactors(num2) # populating factors 2 list
# to find common factors we can use the inbuilt python set functions.
commonFactors = list(set(numberOneFactors).intersection(numberTwoFactors))
# the intersection method finds the common elements in a set.
I'm fairly certain after years of searching that this is not possible, but I'll ask anyway.
The question is whether it's possible to use a dynamic variable in an operation when you don't know the field name. For example, I have a data structure that contains a few hundred fields. The operator selects one of those fields and the program needs to know what data resides in the field from the data structure passed. So we'll say that there are 100 fields, and field50 is what the operator chose to operate on. The program would be passed in the field name (i.e. field50) in the FLDNAM variable. The program would read something like this the normal way:
/free
if field50 = 'XXX'
// do something
endif;
/end-free
The problem is that I would have to code this 100 times for every operation. For example:
/free
if fldnam = 'field1';
// do something
elseif fldnam = 'field2';
// do something
..
elseif fldnam = 'field50';
// do something
endif;
Is there any possible way of performing an operation on a field not yet known? (i.e. IF FLDNAM(pointer data) = 'XXX' then do something)
If the data structure is externally-described and you know what file it comes from, you could use the QUSLFLD API to find out the offset, length, and type of the field in the data structure, and then use substring to get the data and then use other calculations to get the value, depending on the data type.
Simple answer, no.
RPG's simply not designed for that. Few languages are.
You may want to look at scripting languages. Perl for instance, can evaluate on the fly. REXX, which comes installed on the IBM i, has an INTERPRET keyword.
REXX Reference manual
I'm hoping someone can help answer my question, perhaps with an idea of where to go or whether what I'm trying to do is not possible with the way I want to do it.
I've been asked to write a set of rules based on the data held by our ERP form components or variables.
Unfortunately, these components and variables cannot be accessed or used outside of the ERP, so I can't use SQL to query the values and then build some kind of SQL query.
They'd like the ability to put statements like these:
C(MyComponentName) = C(MyOtherComponentName)
V(MyVariableName) > 16
(C(MyComponentName) = "") AND V(MyVariableName) <> "")
((C(MyComponentName) = "") OR C(MyOtherComponentName) = "") AND V(MyVariableName) <> "")
This should be turned into some kind of query which gets the value of MyComponentName and MyOtherComponentName and (in this case) compares them for equality.
They don't necessarily want to just compare for equality, but to be able to determine whether a component / variable value is greaterthan or lessthan etc.
Basically it's a free-form statement that gets converted into something similar to an IF statement.
I've tried this:
Sub TestCondition()
Dim Condition as string = String.Format("{0} = {1}", _
Component("MyComponent").Value, Component("MyOtherComponent").Value)
If (Condition) Then
' Do Something
Else
' Do Something Else
End If
End Sub
Obviously, this does not work and I honestly didn't think it would be so simple.
Ignoring the fact that I'd have to parse the line, extract the required operators, the values from components or variables (denoted by a C or V) - how can I do this?
I've looked at Expression Trees but these were confusing, especially as I'd never heard of them, let alone used them. (Is it possible to create an expression tree for dynamic if statements? - This link provided some detail on expression trees in C#)
I know an easier way to solve this might be to simply populate the form with a multitude of drop-down lists, so users pick what they want from lists or fill in a text box for a specific search criteria.
This wouldn't be a simple matter as the ERP doesn't allow you to dynamically create controls on its forms. You have to drag each component manually and would be next to useless as we'd potentially want at least 1 rule for every form we have (100+).
I'm either looking for someone to say you cannot do this the way you want to do it (with a suitable reason or suggestion as to how I could do it) that I can take to my manager or some hints, perhaps a link or 2 pointing me in the right direction.
If (Condition) Then
This is not possible. There is no way to treat data stored in a string as code. While the above statement is valid, it won't and can't function the way you want it to. Instead, Condition will be evaluated as what it is: a string. (Anything that doesn't boil down to 0 is treated as True; see this question.)
What you are attempting borders on allowing the user to type code dynamically to get a result. I won't say this is impossible per se in VB.Net, but it is incredibly ambitious.
Instead, I would suggest clearly defining what your application can and can't do. Enumerate the operators your code will allow and build code to support each directly. For example:
Public Function TestCondition(value1 As Object, value2 As Object, op as string) As Boolean
Select Case op
Case "="
Return value1 = value2
Case "<"
Return value1 < value2
Case ">"
Return value1 > value2
Case Else
'Error handling
End Select
End Function
Obviously you would need to tailor the above to the types of variables you will be handling and your other specific needs, but this approach should give you a workable solution.
For my particular requirements, using the NCalc library has enabled me to do most of what I was looking to do. Easy to work with and the documentation is quite extensive - lots of examples too.
This is an ugly one. I wish I wasn't having to ask this question, but the project is already built such that we are handling heavy loads of validations in the database. Essentially, I'm trying to build a function that will take two stacks of data, weave them together with an unknown batch of operations or comparators, and produce a long string.
Yes, that was phrased very poorly, so I'm going to give an example. I have a form that can have multiple iterations of itself. For some reason, the system wants to know if the entered start date on any of these forms is equal to the entered end date on any of these forms. Unfortunately, due to the way the system is designed, everything is stored as a string, so I have to format it as a date first, before I can compare. Below is pseudo code, so please don't correct me on my syntax
Input data:
'logFormValidation("to_date(#) == to_date(^)"
, formname.control1name, formname.control2name)'
Now, as I mentioned, there are multiple iterations of this form, and I need to loop build a fully recursive comparison (note: it may not always be typical boolean comparisons, it could be internally called functions as well, so .In or anything like that won't work.) In the end, I need to get it into a format like below so the validation parser can read it.
OR(to_date(formname.control1name.1) == to_date(formname.control2name.1)
,to_date(formname.control1name.2) == to_date(formname.control2name.1)
,to_date(formname.control1name.3) == to_date(formname.control2name.1)
,to_date(formname.control1name.1) == to_date(formname.control2name.2)
:
:
,to_date(formname.control1name.n) == to_date(formname.control2name.n))
Yeah, it's ugly...but given the way our validation parser works, I don't have much of a choice. Any input on how this might be accomplished? I'm hoping for something more efficient than a double recursive loop, but don't have any ideas beyond that
Okay, seeing as my question is apparently terribly unclear, I'm going to add some more info. I don't know what comparison I will be performing on the items, I'm just trying to reformat the data into something useable for ANY given function. If I were to do this outside the database, it'd look something like this. Note: Pseudocode. '#' is the place marker in a function for vals1, '^' is a place marker for vals2.
function dynamicRecursiveValidation(string functionStr, strArray vals1, strArray vals2){
string finalFunction = "OR("
foreach(i in vals1){
foreach(j in vals2){
finalFunction += functionStr.replace('#', i).replace('^', j) + ",";
}
}
finalFunction.substring(0, finalFunction.length - 1); //to remove last comma
finalFunction += ")";
return finalFunction;
}
That is all I'm trying to accomplish. Take any given comparator and two arrays, and create a string that contains every possible combination. Given the substitution characters I listed above, below is a list of possible added operations
# > ^
to_date(#) == to_date(^)
someFunction(#, ^)
# * 2 - 3 <= ^ / 4
All I'm trying to do is produce the string that I will later execute, and I'm trying to do it without having to kill the server in a recursive loop
I don't have a solution code for this but you can algorithmically do the following
Create a temp table (start_date, end_date, formid) and populate it with every date from any existing form
Get the start_date from the form and simply:
SELECT end_date, form_id FROM temp_table WHERE end_date = <start date to check>
For the reverse
SELECT start_date, form_id FROM temp_table WHERE start_date = <end date to check>
If the database is available why not let it do all the heavy lifting.
I ended up performing a cross product of the data, and looping through the results. It wasn't the sort of solution I really wanted, but it worked.
When I´m using MATLAB, sometimes I feel the need to make comments on some variables. I would like to save these comments inside these variables. So when I have to work with many variables in the workspace, and I forget the context of some of these variables I could read the comments I put in every one of them. So I would like to comment variables and keep the comments inside of them.
While I'm of the opinion that the best (and easiest) approach would be to make your variables self-documenting by giving them descriptive names, there is actually a way for you to do what you want using the object-oriented aspects of MATLAB. Specifically, you can create a new class which subclasses a built-in class so that it has an additional property describing the variable.
In fact, there is an example in the documentation that does exactly what you want. It creates a new class ExtendDouble that behaves just like a double except that it has a DataString property attached to it which describes the data in the variable. Using this subclass, you can do things like the following:
N = ExtendDouble(10,'The number of data points')
N =
The number of data points
10
and N could be used in expressions just as any double value would. Using this example subclass as a template, you could create "commented" versions of other built-in numeric classes, with the exception of those you are not allowed to subclass (char, cell, struct, and function_handle).
Of course, it should be noted that instead of using the ExtendDouble class like I did in the above example, I could instead define my variable like so:
nDataPoints = 10;
which makes the variable self-documenting, albeit with a little more typing needed. ;)
How about declaring another variable for your comments?
example:
\>> num = 5;
\>> numc = 'This is a number that contains 5';
\>> whos
...
This is my first post in StackOverflow. Thanks.
A convenient way to solve this is to have a function that does the storing and displaying of comments for you, i.e. something like the function below that will pop open a dialog box if you call it with comments('myVar') to allow you to enter new (or read/update previous) comments to variable (or function, or co-worker) labeled myVar.
Note that the comments will not be available in your next Matlab session. To make this happen, you have to add save/load functionality to comments (i.e. every time you change anything, you write to a file, and any time you start the function and database is empty, you load the file if possible).
function comments(name)
%COMMENTS stores comments for a matlab session
%
% comments(name) adds or updates a comment stored with the label "name"
%
% comments prints all the current comments
%# database is a n-by-2 cell array with {label, comment}
persistent database
%# check input and decide what to do
if nargin < 1 || isempty(name)
printDatabase;
else
updateDatabase;
end
function printDatabase
%# prints the database
if isempty(database)
fprintf('no comments stored yet\n')
else
for i=1:size(database,1)
fprintf('%20s : %s\n',database{i,1},database{i,2});
end
end
end
function updateDatabase
%# updates the database
%# check whether there is already a comment
if size(database,1) > 0 && any(strcmp(name,database(:,1)))
idx = strcmp(name,database(:,1));
comment = database(idx,2);
else
idx = size(database,1)+1;
comment = {''};
end
%# ask for new/updated comment
comment = inputdlg(sprintf('please enter comment for %s',name),'add comment',...
5,comment);
if ~isempty(comment)
database{idx,1} = name;
database(idx,2) = comment;
end
end
end
Always always always keep the Matlab editor open with a script documenting what you do. That is, variable assignments and calculations.
Only exceptions are very short sessions where you want to experiment. Once you have something -- add it to the file (It's also easier to cut and paste when you can see your entire history).
This way you can always start over. Just clear all and rerun the script. You never have random temporaries floating around in your workspace.
Eventually, when you are finished, you will also have something that is close to 'deliverable'.
Have you thought of using structures (or cells, although structures would require extra memory use)?
'>> dataset1.numerical=5;
'>> dataset1.comment='This is the dataset that contains 5';
dataset1 =
numerical: 5
comment: 'This is the dataset that contains 5'