Challenge 12 Megathread

#1

Welcome to challenge 12! Use this thread for any and all questions relating to challenge 12.

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#2
#3
#4

image

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#5

Again, Array#filter allows us to write a nice, compact solution:

const checkAir = (samples, threshold) => samples.filter(i => i > "d").length / samples.length < threshold ? "Clean" : "Polluted"
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#6 
const checkAir = function (samples, threshold) {
  return (samples.filter(sample => sample == 'dirty').length / samples.length) > threshold ? 'Polluted' : 'Clean';
}
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#7

Exact same solution hehe:

const checkAir = (samples, threshold)=>{
  if ((samples.filter(sample=>sample=='dirty').length/samples.length)<threshold){
    return 'Clean'
  }else return 'Polluted'
}
2 Likes
#8 
const checkAir = function (samples, threshold) {
  // Code here!

  let countSample = 0;
  
  for(var sample in samples){
    if(sample === 'dirty')
      countSample ++;
      var pollution = countSample / samples.length;
       
    if (pollution >= threshold){
      return "Polluted";
    } 
    else if (pollution <=threshold ){
      
      return 'Clean';
    }
    
  }
    
   };

I didn’t pass a test:
Failed: If there are too many dirty samples, then the function should return "Polluted"

Reason: Your code ran but did not produce the correct result.

Hint: Check to see that the ratio of dirty samples to total samples is within the threshold.

Failing Test Code:

      const samples = ['clean', 'clean', 'dirty', 'clean', 'dirty', 'clean', 'clean', 'dirty', 'clean', 'dirty']
      const threshold = 0.3

      const result = checkAir(samples, threshold)

      assert.equal(result, 'Polluted')

Expected: Polluted

Actual: Clean

1 Like
#9

you didn’t close your for loop after incrementing countSample. Also if pollution == threshold what happens? the else if should be less than instead of less than or equal to I think (:

#10

I will show what I think it is wrong.

const checkAir = function (samples, threshold) {
// Code here!

let countSample = 0;

for(var sample in samples){
if(sample === ‘dirty’)
countSample ++;
// you need to do this after the for loop finish
var pollution = countSample / samples.length;

if (pollution >= threshold){
  return "Polluted";
} 
else if (pollution <=threshold ){
  
  return 'Clean';
}

}

};

Fixed:
const checkAir = function (samples, threshold) {
// Code here!

let countSample = 0;

for(var sample in samples){
if(sample === ‘dirty’)
countSample ++;
}
var pollution = countSample / samples.length;

if (pollution >= threshold){
  return "Polluted";
} 
else if (pollution <=threshold ){      
  return 'Clean';
}

};

#11

Great! kindly explain this line
samples.filter(i => > 'd')

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#12

your function is not returning the right result… and i notice you’re trying to return from your for loop

#13

Check your code correctly, indent it so you will be understand what you’ve written and no where error are

#14

We use Array#filter to pick out the elements in samples that satisfy the given boolean test: for every element (represented by the variable i), check if it is greater than "d".

By lexicological order, "dirty" > "d" and "clean" < "d", so we use this line with the .length property to count the number of occurrences of "dirty" in samples.

#15

const checkAir = function (samples, threshold) {

dirty = 0;
for (var sample in samples) {
if (sample == “dirty”) {
dirty = count++;}
let dirtnew = dirty / samples.length;
if (dirtnew > threshold) {
return ‘Polluted’;}
return ‘Clean’;
}
// Code here!
};

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#16

Thanks so much but what “d”? is it the first letter of dirty?

#17 
const checkAir = (samples, threshold) =>
  samples.filter(sample => sample === "dirty").length / samples.length <
  threshold
    ? "Clean"
    : "Polluted";
#18

what’s the count++ doing? it should be

#19 
if(sample == 'dirty){
return dirty++
}
#20

"d" is just a string with a single letter in it. I just use that because, alphabetically, "clean" < "d" and "d" < "dirty".

1 Like