Streaming multiple traces to multiple plots with Arduino and Plotly

multiple.ino

#include <SPI.h>
#include <Ethernet.h>
#include "plotly_streaming_ethernet.h"
 
// View your API key and streamtokens here: https://plot.ly/settings
#define nTracesT 2
#define nTracesH 2

// View your tokens here: https://plot.ly/settings
// Supply as many tokens as data traces
// e.g. if you want to ploty A0 and A1 vs time, supply two tokens
char *tokens1[nTracesT] = {"your_token_1", "your_token_2"};
char *tokens2[nTracesH] = {"your_token_3", "your_token_4"};

// arguments: username, api key, streaming token, filename
plotly graph1 = plotly("your_username", "your_api_key", tokens1, "graph1", nTracesT);
plotly graph2 = plotly("your_username", "your_api_key", tokens2, "graph2", nTracesH);
 
byte mac[] = {  
  0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02 };

EthernetClient client;

void startEthernet(){
// start the Ethernet connection:
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    for(;;)
      ;
  }
  // print your local IP address:
  Serial.print("My IP address: ");
  for (byte thisByte = 0; thisByte < 4; thisByte++) {
    // print the value of each byte of the IP address:
    Serial.print(Ethernet.localIP()[thisByte], DEC);
    Serial.print("."); 
  }
  Serial.println();
  
}
 
 void setup() {
 
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }
 
  startEthernet();
 
  bool success1, success2;
  success1 = graph1.init();
  if(!success1){while(true){}}
  success2 = graph2.init();
  if(!success2){while(true){}}  
  graph2.openStream();
}
 
unsigned long x;
int y;
 
void loop() {
   graph2.plot(millis(), analogRead(A0), tokens1[0]);
   graph2.plot(millis(), analogRead(A0)+10, tokens1[1]);  
   graph2.plot(millis(), analogRead(A1)+400, tokens2[0]);
   graph2.plot(millis(), analogRead(A1)+500, tokens2[1]);

  delay(25);
 
}

It's confusing that we plot to graph2 in the loop. In the plotly library, each graph holds a connection to plotly's servers. However, the Arduino can only hold 1 connection open at a time, so when graph2 initializes (graph2.init()), the graph1 connection is closed. This is OK, because all plotly's streaming servers need are the stream tokens!