# Arduino code techniques

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This page shows common code techniques that can be useful on the Arduino.

# Mean filter

Problem: you have multiple ADC measurements (battery, ultrasonic etc.) that can contain outliers. What value is the 'most seen value'? Solution: This code will sort and choose the center value. Example: Measurements: 32,7,7,1,6,8,7,9,23,7,8,9,7 Sorted: 1,6,7,7,7,7,7,8,8,9,9,23,32 Returned: 7 (center value)

```unsigned int ADCmedian(int pin, int count) {
int values[count], last;
uint8_t j, i = 0;
values = 0;
while (i < count) {
last = analogRead(pin);
if (i > 0) {
for (j = i; j > 0 && values[j - 1] < last; j--) // Insertion sort loop.
values[j] = values[j - 1]; // Shift ping array to correct position for sort insertion.
} else j = 0;              // First ping is starting point for sort.
values[j] = last;              // Add last ping to array in sorted position.
i++;                       // Move to next ping.
if (i < count) delay(1);
}
return (values[count/2]); // Return the median.
}
```