Why creating a new variable and using it when you can use the old variable?

creating a new variable with existing data points is referred to as
create a new variable in sas using if-then
creating a new variable with existing data points is called
how do you create a variable and assign it a value
which of the following statements is used to declare variables in the data step
statements are used to create new variables python
create new column in sas
sas create variables from values

Why do we need to :-

  1. Create a View x.
  2. Then set x = a
  3. Then use a if command on x if you can directly use a.

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
    
        // check if the current view is reused else inflate the view
        View listItemView = convertView;
    
        if(listItemView == null){
            listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
        }
    

Instead , Why can't we do this?

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    if(convertView == null){
        convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
    }

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

Creating New Variables - SPH, How do I create a new variable from an existing variable in SAS? The New-Variable cmdlet creates a new variable in PowerShell. You can assign a value to the variable while creating it or assign or change the value after it is created. You can use the parameters of New-Variable to set the properties of the variable, set the scope of a variable, and determine whether variables are public or private. Typically, you create a new variable by typing the variable

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

Why should a variable be declared as static and final, Why should a variable not be declared as a model variable? Retains the old value. If some values don't require recoding, use this to include the old values. Any old values that are not specified are not included in the new variable, and cases with those values will be assigned the system-missing value for the new variable. Output variables are strings. Defines the new, recoded variable as a string

As the develeoper in some cases wanted to assign a value LayoutInflater.from(...).inflate(...), different from the argument convertView, he chose not to overwrite the argument, but to introduce a new variable. It's good style not to modify method arguments.

So, in the case that convertView is null, listItemView gets a value from the LayoutInflater call, to be used further down the method. And the fact that the method was called with a null argument is still visible.

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?
        convertView :
        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

What is Variable? Webopedia Definition, What does the operation recode into different variables do to the data? I would like to create a new variable which elements are named after the elements of an existing variable, but with str_replace_all, it works only for the first cases Thank you df<-data.frame

Chapter 16: Multiple choice questions, new value based on the current value of "height_in_inches" There are only a few things you can do with a variable: Create one (with a nice name). When you assign a value to a variable, you replace the old value with a new one. The old  We would like to create a new data set with a new variable, BMI, or body mass index, based on height and weight. To create a new variable choose a name for the new variable, use a data step, and then define it based on already existing variables using the equals sign (=). Examples . YearAge65 = byear+65; income = salary + interest + dividends;

Programming - Variables, As a rule, you only reuse a variable if it needs to hold a new primitive value or point to a different object, because it is the variable that represents the current state. If the variable is reassigned to hold something that means something different, you should not do that but use a new variable. Creating New Variables Using if-then; if-then-else; and if-then-else-then Statements An if-then statement can be used to create a new variable for a selected subset of the observations. For each observation in the data set, SAS evaluates the expression following the if .

which is faster, creating new variable vs reusing old variable , Then when you are done, you can use these files to create a do-file to everything you have done starting with the original data. If you drop three variables from pcoms1.dta and create two new variables, call the new file pcoms2.dta. This module shows how to create and recode variables. In SPSS you can create new variables with compute and you can modify the values of an existing variable with recode. 1. Computing new variables. Let’s use the auto data for our examples. In this section we will see how to create new variables with compute.

Comments
  • Not recommented to change the original data.
  • Thanks, Can you elaborate on "Inflate operations some expensive"
  • See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.
  • Can you explain a little more , like why the second code is also valid.
  • It is valid because it works. Can you explain a little more, like why the second code is not valid?
  • I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.
  • You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.