I have a list of words allWords and I am trying to create a new list from allWords containing only those words that begin with a specific letter currLetter. Looking at the docs, collection.map() seems like a great choice. However the statement below won't compile since .starts(with: ) returns a boolean.
targetWords = allWords.map { $0.starts(with: currLetter) }
Can anyone point me in the right direction?
While not described in the documentation of collection type instance methods, the solution is to use filter() instead of map():
targetWords = allWords.filter { $0.starts(with: currLetter) }
Related
Using ag-grid 23.2.1, it looks like our current approach to filtering is on it's way out and listed as deprecated. Reading over the setModel documentation, I don't readily see a way to replace some of our selectValue, selectNothing, etc. usage.
Example 1: we clear the selection and then pick a couple of values on some condition else we select all
let filterInstance = this.gridOptions.api.getFilterInstance('make');
this.cacheFilterModel = this.gridOptions.api.getFilterModel();
if (condition) {
filterInstance.selectNothing();
filterInstance.selectValue('thing1');
filterInstance.selectValue('thing2');
}
else {
filterInstance.selectEverything();
}
filterInstance.applyModel();
this.gridOptions.api.onFilterChanged();
Example 2: we have some filter values in a column toggle-able via checkboxes, which call a method like the below. if one of the values is checked it gets added to the existing filter, if unchecked the value is removed. There could be values already filtered and I don't really see a way to contextually select/unselect values using setModel.
filterExample (make, add) {
let filterInstance = this.gridOptions.api.getFilterInstance('make');
if (add) {
filterInstance.selectValue(make);
}
else {
filterInstance.unselectValue(make);
}
filterInstance.applyModel();
this.gridOptions.api.onFilterChanged();
}
Are there setModel equivalents for these?
I had a similar issue with setColumnFilter where I had to pass a few values. You can use filterInstance.setModel to set these values by passing an array like so:
filterInstance.setModel({ values: ['value1', 'value2'] })
filterInstance.applyModel();
gridOptions.api.onFilterChanged()
here is a link to how to do it from the docs. I found this hard to find on google so providing it here.
https://www.ag-grid.com/javascript-grid-filter-set-api/
With arrays you can use a subscript to access Array Elements directly. You can read or write to them. With Sets I am not sure of a way to write its Elements.
For example, if I access a set element matching a condition I'm only able to read the element. It is passed by copy and I can't therefore write to the original.
For example:
columns.first(
where: {
$0.header.last == Character(String(i))
}
)?.cells.append(value: addValue)
// ERROR: Cannot use mutating member on immutable value: function call returns immutable value
You can't just change things inside a set, because of how a (hash) set works. Changing them would possibly change their hash value, making the set into an invalid state.
Therefore, you would have to take the thing you want to change out of the set, change it, then put it back.
if var thing = columns.first(
where: {
$0.header.last == Character(String(i))
}) {
columns.remove(thing)
thing.cells.append(value: addValue)
columns.insert(thing)
}
If the == operator on Column doesn't care about cells (i.e. adding cells to a column doesn't suddenly make two originally equal columns unequal and vice versa), then you could use update instead:
if var thing = columns.first(
where: {
$0.header.last == Character(String(i))
}) {
thing.cells.append(value: addValue)
columns.update(thing)
}
As you can see, it's quite a lot of work, so maybe sets aren't a suitable data structure to use in this situation. Have you considered using an array instead? :)
private var _columns: [Column]
public var columns : [Column] {
get { _columns }
set { _columns = Array(Set(newValue)) }
// or any other way to remove duplicate as described here: https://stackoverflow.com/questions/25738817/removing-duplicate-elements-from-an-array-in-swift
}
You are getting the error because columns might be a set of struct. So columns.first will give you an immutable value. If you were to use a class, you will get a mutable result from columns.first and your code will work as expected.
Otherwise, you will have to do as explained by #Sweeper in his answer.
I've searched a lot but can't find a clear answer anywhere for string list -> enum.
I've got a list of strings that I want to turn into an enum that I can select from in Unity inspector.
Specifically, I'm trying to make an enum list of all the currently set-up Input buttons from project settings. I've got all the names, just don't know how to make it an enum or similar. Ideally showing up like a KeyCode variable in inspector.
Currently trying (and failing) with:
foreach (string s in names)
{
if (Enum.TryParse(s, true, out list))
Debug.Log(list);
else Debug.Log("FAILED");
}
"names" = static List<string> names;
"list" = static MyList list;
"MyList" = enum MyList { Null }
Returns "FAILED" 58 times for only 29 Input axis.
I want a simple solution, so if its not possible or relatively simple, I'll work out something else.
Code for getting the "names" list of strings (Works correctly):
var inputManager = AssetDatabase.LoadAllAssetsAtPath("ProjectSettings/InputManager.asset")[0];
SerializedObject obj = new SerializedObject(inputManager);
SerializedProperty axisArray = obj.FindProperty("m_Axes");
if (axisArray.arraySize == 0)
Debug.Log("No Axes");
for (int i = 0; i < axisArray.arraySize; ++i)
{
var axis = axisArray.GetArrayElementAtIndex(i);
var name = axis.FindPropertyRelative("m_Name").stringValue;
names.Add(name);
}
Normally you can do
foreach (string colorName in Enum.GetNames(typeof(Colors))) which will iterate the names of the enums.
In your code above you havent shown what list is, nor where names has come from. However.
enum Things
{
Item1 = 0,
Item2 = 1
}
You can get the name from string name = Enum.GetName(typeof(Things), (int)Things.Item2) and you can get values from names with int value = (int)Enum.Parse(typeof(Things), nameOfThing)
So depending on what you actually want in a list and what you start with, iterate through and pick the relevant one
I ended up making my own solution, since (and please correct me if I'm wrong) the TryParse() and Parse() methods appear to need the enum to already contain entries with the same name (or index int) as the string to parse. This defeats the purpose for me, since I am doing this because I don't have the names in there already.
My solution ended up being to switch to having a single string input variable instead of an enum, then use Odin Inspector's ValidateInput attribute to check (for spelling errors, and) if the input variable matches any of the string entries in my dynamic list of InputManager input names (which I update manually using Odin Inspector's Button attribute and the code in the original post).
It's slightly less clean than I wanted, but does the job, so I'm satisfied.
I have an array of words, some may or may not have typos.
potentialWords = ["hello", "lkasjdf", "hunry"]
What I want to do is, return an array of all valid words, and also those words that were able to be autocorrected using a function I created correctWord. It returns an array of potential matches. so "hunry" might return ["hungry", "hurry"]. I will select the first index for the best guess.
Some words cannot be corrected however! e.g. "lkasjdf" will not find any corrections, but "hunry" will.
I was trying something like:
potentialWords.map {
if correctWord($0) != nil {
return correctWord($0)[0]
}
}
of course this will complain and say that I need a return outside the if clause. I can filter the list based on if the word can be corrected, and then map over the filtered list, re-checking which words need to be corrected, but this runs the correctWord function way too many times, and it is very sensitive.
I would like to be able to do one single pass through, and return an array of all valid words, and also corrected words.
P.S. I am calling correctWord twice in the map function for brevity, but of course I would assign correctWord($0) to a variable, and then if it isn't nil, take the first index and add it to the new list.
I think you're after flatMap. It's the same as map except it will also filter out any nil values.
potentialWords.flatMap { correctWord($0)?.first }
I don't understand how to describe #helper.repeat in play2.2.1.
#helper.form(action = routes.Application.send) {
#helper.repeat(
field = form1("input"), min = 3
) {fld =>
#helper.inputText(
field = fld, '_label ->"input"
)
}
}
It is the part fld => #helper.inputText(field = fld) that I can't understand.
What does it mean?
I know Java, so I assume it is a functional writing, but in above code, where does the variable fld come from?
And why the tip of the arrow indicates #helper.inputText(field = fld)?
why is fld the value of field in #helper.inputText?
I have googled, but I couldn't find an enough explanation for a beginner.
I am not sure of Scala's grammar.
Please explain above code for a beginner?
Original Answer
This seems to be a bit overcomplicated. There is no need to assign values by hand. Usually you would write a repeater like this:
#helper.repeat(form1("input"), min = 3) { fld =>
#helper.inputText(fld, '_label ->"input")
}
In functional programming this is a so called higher-order function. You may know other scala built in higher-order functions like map, filter or foreach. #helper.repeat is very similar to foreach. form1("input") refers to a collection of values you want to display. min = 1 tells the repeater to show at least one field. Finally within { fld => ... } you iterate over all values defined in your collection.
In other words: { fld => ... } is just an anonymous function that takes a single Field parameter (fld) and displays a text input for that specific field.
Follow Up
Ok, I'm trying to follow up your questions from the comments. Let's start by the signature of helper.repeat. There is no magic involved here, it's just a regular Scala function:
helper.repeat(field: Field, min: Int)(fieldRenderer: (fld: Field) => Html): Seq[Html]
In Scala, functions can have multiple parameter lists. Here we have two. The first parameter list takes two parameters: field and min. The second parameter list takes a single function as parameter: fieldRenderer. fieldRenderer itself takes again a single parameter (fld) and returns Html.
The important thing is, you are not passing "data" but a function instead. To clear this up:
The signature fieldRenderer: (fld: Field) => Html
is equal to def fieldRenderer(fld: Field): Html
This means, you can do anything within this function, as long as it returns Html. That's exactly what happens in the example at the very top. You pass a Field and return Html. You do that by calling #helper.inputText.
Now repeat first gets a List[Field] from field you pass as first parameter. This list corresponds to the String List of your container class. Also repeat ensures there is at least one element in that list. This is, because you passed 1 as min. Then the function fieldRenderer is applied to all elements in our list.
A pseudo code implementation of repeat could look like this:
def repeat(field: Field, min: Int)(fieldRenderer: (fld: Field) => Html): Seq[Html] {
val list: List[Field] = field.getFields
var output: List[Html] = List()
for (i = 0; i < list.length; i++) {
val element: Field = list.get(i)
val html: Html = fieldRenderer(element)
output += html
}
return output
}