How to Create Dynamic Variable Names Inside a Loop

How do I create dynamic variable names inside a loop?

Use an array for this.

var markers = [];
for (var i = 0; i < coords.length; ++i) {
    markers[i] = "some stuff";
}

How do you create different variable names while in a loop?

Sure you can; it's called a dictionary:

d = {}
for x in range(1, 10):
    d["string{0}".format(x)] = "Hello"

>>> d["string5"]
'Hello'
>>> d
{'string1': 'Hello',
 'string2': 'Hello',
 'string3': 'Hello',
 'string4': 'Hello',
 'string5': 'Hello',
 'string6': 'Hello',
 'string7': 'Hello',
 'string8': 'Hello',
 'string9': 'Hello'}

I said this somewhat tongue in check, but really the best way to associate one value with another value is a dictionary. That is what it was designed for!

Dynamic variable names to mutate variables in for-loop

As we are passing string, convert to symbol and evaluate (!!)

func <- function(i) {
   
   mutate(df1, !!i := case_when(!is.na(!! rlang::ensym(i)) ~ as.character(!! rlang::ensym(i)),
                              is.na(!!rlang::ensym(i)) & var0 != '1' ~ '4444',
                              TRUE ~ '0'))
 }

-testing

for(i in vars) {
   df1 <- func(i)
 }
df1
  var0 var1 var2 var3
1    1    0    1   NA
2    2    1 4444    1
3    2    0    0    0
4    1    1    0 4444
5    1    0    1    1
6    2 4444 4444   NA
7    2 4444 4444    1  

---

We may do this with across as well

df1 %>%
    mutate(across(all_of(vars), 
    ~ case_when(!is.na(.) ~ as.character(.), 
       is.na(.) & var0 != '1' ~ '4444', TRUE ~ '0')))
  var0 var1 var2 var3
1    1    0    1   NA
2    2    1 4444    1
3    2    0    0    0
4    1    1    0 4444
5    1    0    1    1
6    2 4444 4444   NA
7    2 4444 4444    1

JavaScript: Dynamically Creating Variables for Loops

You should use an array:

function createVariables(){
  var accounts = [];

  for (var i = 0; i <= 20; ++i) {
      accounts[i] = "whatever";
  }

  return accounts;
}

You then have access to accounts[0] through accounts[20].

Dynamic variable in loop javascript

You don't want to create 9 variables. Trust me. You want to create an object.

var m = {};
for(var i=1; i<10; i++){
    m[i] = "Something";
}

You can also create an array (m = []), but since you are starting at 1 and not 0, I'd suggest an object.

R: Read dynamic variable names generated in for loop

You may use get to do this -

library(dplyr)

for (i in 1:nrow(LabviewFiles)){
  assign(x = paste("P",i , "Onsets_PRH", sep = "_"), value = t(subset.data.frame(All_Phase, All_Phase$Phase==i) %>% 
                                                                 filter(CONDITIONS == "NULL_TRIAL",
                                                                        MISC_REWARD == 1,
                                                                        MISC_PASSIVE_FAILED == 1) %>% 
                                                                 select(Feedback_onset)))

  assign(x = paste("P",i , "Durations_PRH", sep = "_"), value = t(rep(0.5, times = length(get(paste("P",i , "Onsets_PRH", sep = "_"))))))
}

Note that using assign and creating variables in global environment is discouraged. You may also read Why is using assign bad?

How to create variable names with a for loop?

Creating variables dynamically is an anti-pattern and should be avoided. What you need is actually a list:

total_squares = 8
box_list = []
boxes = [0] * total_squares
for q in range(total_squares):
  box_list.append(boxes[q])

Then you can refer to any element you want (say, box_i) using the following syntax:

my_box = box_list[boxes[i]]

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