#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
#include <avr/power.h>
#endif

// Pin connected to the NeoPixels
#define PIN            6

//NeoPixels attached to the Arduino
#define NUMPIXELS      16

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);
int i = 0;
int delayval = 20; // delay for half a second
int color;
int force = A0;
int value = 0;
void setup() {
  pinMode(A0, INPUT);
  Serial.begin(9600);
  pixels.begin(); // This initializes the NeoPixel library.
}

void loop() {
  value = analogRead(force);//Read sensor's pin.
  value = map(value, 0, 1023, 0, pixels.numPixels());

  for (i = 0; i <= value; i++) {
    pixels.setPixelColor(i, pixels.Color(i*16, 0, 255-i*16));
  }
  for (int k = pixels.numPixels(); k >= i; k--) {
    pixels.setPixelColor(k, pixels.Color(0, 0, 0));
  }
  pixels.show();
}