dygraph-tickers.js

   1 /**
   2  * @license
   3  * Copyright 2011 Dan Vanderkam (danvdk@gmail.com)
   4  * MIT-licensed (http://opensource.org/licenses/MIT)
   5  */
   6
   7 /**
   8  * @fileoverview Description of this file.
   9  * @author danvk@google.com (Dan Vanderkam)
  10  *
  11  * A ticker is a function with the following interface:
  12  *
  13  * function(a, b, pixels, options_view, dygraph, forced_values);
  14  * -> [ { v: tick1_v, label: tick1_label[, label_v: label_v1] },
  15  *      { v: tick2_v, label: tick2_label[, label_v: label_v2] },
  16  *      ...
  17  *    ]
  18  *
  19  * The returned value is called a "tick list".
  20  *
  21  * Arguments
  22  * ---------
  23  *
  24  * [a, b] is the range of the axis for which ticks are being generated. For a
  25  * numeric axis, these will simply be numbers. For a date axis, these will be
  26  * millis since epoch (convertable to Date objects using "new Date(a)" and "new
  27  * Date(b)").
  28  *
  29  * opts provides access to chart- and axis-specific options. It can be used to
  30  * access number/date formatting code/options, check for a log scale, etc.
  31  *
  32  * pixels is the length of the axis in pixels. opts('pixelsPerLabel') is the
  33  * minimum amount of space to be allotted to each label. For instance, if
  34  * pixels=400 and opts('pixelsPerLabel')=40 then the ticker should return
  35  * between zero and ten (400/40) ticks.
  36  *
  37  * dygraph is the Dygraph object for which an axis is being constructed.
  38  *
  39  * forced_values is used for secondary y-axes. The tick positions are typically
  40  * set by the primary y-axis, so the secondary y-axis has no choice in where to
  41  * put these. It simply has to generate labels for these data values.
  42  *
  43  * Tick lists
  44  * ----------
  45  * Typically a tick will have both a grid/tick line and a label at one end of
  46  * that line (at the bottom for an x-axis, at left or right for the y-axis).
  47  *
  48  * A tick may be missing one of these two components:
  49  * - If "label_v" is specified instead of "v", then there will be no tick or
  50  *   gridline, just a label.
  51  * - Similarly, if "label" is not specified, then there will be a gridline
  52  *   without a label.
  53  *
  54  * This flexibility is useful in a few situations:
  55  * - For log scales, some of the tick lines may be too close to all have labels.
  56  * - For date scales where years are being displayed, it is desirable to display
  57  *   tick marks at the beginnings of years but labels (e.g. "2006") in the
  58  *   middle of the years.
  59  */
  60
  61 /*jshint globalstrict: true */
  62 /*global Dygraph:false */
  63 "use strict";
  64
  65 /** @typedef {Array.<{v:number, label:string, label_v:(string|undefined)}>} */
  66 Dygraph.TickList;
  67
  68 /** @typedef {function(
  69  *    number,
  70  *    number,
  71  *    number,
  72  *    function(string):*,
  73  *    Dygraph=,
  74  *    Array.<number>=
  75  *  ): Dygraph.TickList}
  76  */
  77 Dygraph.Ticker;
  78
  79
  80 /** @type {Dygraph.Ticker} */
  81 Dygraph.numericLinearTicks = function(a, b, pixels, opts, dygraph, vals) {
  82   var nonLogscaleOpts = function(opt) {
  83     if (opt === 'logscale') return false;
  84     return opts(opt);
  85   };
  86   return Dygraph.numericTicks(a, b, pixels, nonLogscaleOpts, dygraph, vals);
  87 };
  88
  89 /** @type {Dygraph.Ticker} */
  90 Dygraph.numericTicks = function(a, b, pixels, opts, dygraph, vals) {
  91   // This masks some numeric issues in older versions of Firefox,
  92   // where 1.0/Math.pow(10,2) != Math.pow(10,-2).
  93   /** @type {function(number,number):number} */
  94   var pow = function(base, exp) {
  95     if (exp < 0) {
  96       return 1.0 / Math.pow(base, -exp);
  97     }
  98     return Math.pow(base, exp);
  99   };
 100
 101   var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel'));
 102   var ticks = [];
 103   var i, j, tickV, nTicks;
 104   if (vals) {
 105     for (i = 0; i < vals.length; i++) {
 106       ticks.push({v: vals[i]});
 107     }
 108   } else {
 109     // TODO(danvk): factor this log-scale block out into a separate function.
 110     if (opts("logscale")) {
 111       nTicks  = Math.floor(pixels / pixels_per_tick);
 112       var minIdx = Dygraph.binarySearch(a, Dygraph.PREFERRED_LOG_TICK_VALUES, 1);
 113       var maxIdx = Dygraph.binarySearch(b, Dygraph.PREFERRED_LOG_TICK_VALUES, -1);
 114       if (minIdx == -1) {
 115         minIdx = 0;
 116       }
 117       if (maxIdx == -1) {
 118         maxIdx = Dygraph.PREFERRED_LOG_TICK_VALUES.length - 1;
 119       }
 120       // Count the number of tick values would appear, if we can get at least
 121       // nTicks / 4 accept them.
 122       var lastDisplayed = null;
 123       if (maxIdx - minIdx >= nTicks / 4) {
 124         for (var idx = maxIdx; idx >= minIdx; idx--) {
 125           var tickValue = Dygraph.PREFERRED_LOG_TICK_VALUES[idx];
 126           var pixel_coord = Math.log(tickValue / a) / Math.log(b / a) * pixels;
 127           var tick = { v: tickValue };
 128           if (lastDisplayed === null) {
 129             lastDisplayed = {
 130               tickValue : tickValue,
 131               pixel_coord : pixel_coord
 132             };
 133           } else {
 134             if (Math.abs(pixel_coord - lastDisplayed.pixel_coord) >= pixels_per_tick) {
 135               lastDisplayed = {
 136                 tickValue : tickValue,
 137                 pixel_coord : pixel_coord
 138               };
 139             } else {
 140               tick.label = "";
 141             }
 142           }
 143           ticks.push(tick);
 144         }
 145         // Since we went in backwards order.
 146         ticks.reverse();
 147       }
 148     }
 149
 150     // ticks.length won't be 0 if the log scale function finds values to insert.
 151     if (ticks.length === 0) {
 152       // Basic idea:
 153       // Try labels every 1, 2, 5, 10, 20, 50, 100, etc.
 154       // Calculate the resulting tick spacing (i.e. this.height_ / nTicks).
 155       // The first spacing greater than pixelsPerYLabel is what we use.
 156       // TODO(danvk): version that works on a log scale.
 157       var kmg2 = opts("labelsKMG2");
 158       var mults;
 159       if (kmg2) {
 160         mults = [1, 2, 4, 8];
 161       } else {
 162         mults = [1, 2, 5];
 163       }
 164       var scale, low_val, high_val;
 165       for (i = -10; i < 50; i++) {
 166         var base_scale;
 167         if (kmg2) {
 168           base_scale = pow(16, i);
 169         } else {
 170           base_scale = pow(10, i);
 171         }
 172         var spacing = 0;
 173         for (j = 0; j < mults.length; j++) {
 174           scale = base_scale * mults[j];
 175           low_val = Math.floor(a / scale) * scale;
 176           high_val = Math.ceil(b / scale) * scale;
 177           nTicks = Math.abs(high_val - low_val) / scale;
 178           spacing = pixels / nTicks;
 179           // wish I could break out of both loops at once...
 180           if (spacing > pixels_per_tick) break;
 181         }
 182         if (spacing > pixels_per_tick) break;
 183       }
 184
 185       // Construct the set of ticks.
 186       // Allow reverse y-axis if it's explicitly requested.
 187       if (low_val > high_val) scale *= -1;
 188       for (i = 0; i < nTicks; i++) {
 189         tickV = low_val + i * scale;
 190         ticks.push( {v: tickV} );
 191       }
 192     }
 193   }
 194
 195   // Add formatted labels to the ticks.
 196   var k = 1;
 197   var k_labels = [];
 198   var m_labels = [];
 199   if (opts("labelsKMB")) {
 200     k = 1000;
 201     k_labels = [ "K", "M", "B", "T", "Q" ];
 202   }
 203   if (opts("labelsKMG2")) {
 204     if (k) Dygraph.warn("Setting both labelsKMB and labelsKMG2. Pick one!");
 205     k = 1024;
 206     k_labels = [ "k", "M", "G", "T", "P", "E", "Z", "Y" ];
 207     m_labels = [ "m", "u", "n", "p", "f", "a", "z", "y" ];
 208   }
 209
 210   var formatter = /**@type{AxisLabelFormatter}*/(opts('axisLabelFormatter'));
 211
 212   // Add labels to the ticks.
 213   var digitsAfterDecimal = /** @type{number} */(opts('digitsAfterDecimal'));
 214   for (i = 0; i < ticks.length; i++) {
 215     if (ticks[i].label !== undefined) continue;  // Use current label.
 216     tickV = ticks[i].v;
 217     var absTickV = Math.abs(tickV);
 218     // TODO(danvk): set granularity to something appropriate here.
 219     var label = formatter(tickV, 0, opts, dygraph);
 220     if (k_labels.length > 0) {
 221       // TODO(danvk): should this be integrated into the axisLabelFormatter?
 222       // Round up to an appropriate unit.
 223       var n = pow(k, k_labels.length);
 224       for (j = k_labels.length - 1; j >= 0; j--, n /= k) {
 225         if (absTickV >= n) {
 226           label = Dygraph.round_(tickV / n, digitsAfterDecimal) + k_labels[j];
 227           break;
 228         }
 229       }
 230     }
 231     if(opts("labelsKMG2")){
 232       tickV = String(tickV.toExponential());
 233       if(tickV.split('e-').length === 2 && tickV.split('e-')[1] >= 3 && tickV.split('e-')[1] <= 24){
 234         if(tickV.split('e-')[1] % 3 > 0) {
 235           label = Dygraph.round_(tickV.split('e-')[0] /
 236               pow(10,(tickV.split('e-')[1] % 3)),
 237               digitsAfterDecimal);
 238         } else {
 239           label = Number(tickV.split('e-')[0]).toFixed(2);
 240         }
 241         label += m_labels[Math.floor(tickV.split('e-')[1] / 3) - 1];
 242       }
 243     }
 244     ticks[i].label = label;
 245   }
 246
 247   return ticks;
 248 };
 249
 250
 251 /** @type {Dygraph.Ticker} */
 252 Dygraph.dateTicker = function(a, b, pixels, opts, dygraph, vals) {
 253   var chosen = Dygraph.pickDateTickGranularity(a, b, pixels, opts);
 254
 255   if (chosen >= 0) {
 256     return Dygraph.getDateAxis(a, b, chosen, opts, dygraph);
 257   } else {
 258     // this can happen if self.width_ is zero.
 259     return [];
 260   }
 261 };
 262
 263 // Time granularity enumeration
 264 // TODO(danvk): make this an @enum
 265 Dygraph.SECONDLY = 0;
 266 Dygraph.TWO_SECONDLY = 1;
 267 Dygraph.FIVE_SECONDLY = 2;
 268 Dygraph.TEN_SECONDLY = 3;
 269 Dygraph.THIRTY_SECONDLY  = 4;
 270 Dygraph.MINUTELY = 5;
 271 Dygraph.TWO_MINUTELY = 6;
 272 Dygraph.FIVE_MINUTELY = 7;
 273 Dygraph.TEN_MINUTELY = 8;
 274 Dygraph.THIRTY_MINUTELY = 9;
 275 Dygraph.HOURLY = 10;
 276 Dygraph.TWO_HOURLY = 11;
 277 Dygraph.SIX_HOURLY = 12;
 278 Dygraph.DAILY = 13;
 279 Dygraph.WEEKLY = 14;
 280 Dygraph.MONTHLY = 15;
 281 Dygraph.QUARTERLY = 16;
 282 Dygraph.BIANNUAL = 17;
 283 Dygraph.ANNUAL = 18;
 284 Dygraph.DECADAL = 19;
 285 Dygraph.CENTENNIAL = 20;
 286 Dygraph.NUM_GRANULARITIES = 21;
 287
 288 /** @type {Array.<number>} */
 289 Dygraph.SHORT_SPACINGS = [];
 290 Dygraph.SHORT_SPACINGS[Dygraph.SECONDLY]        = 1000 * 1;
 291 Dygraph.SHORT_SPACINGS[Dygraph.TWO_SECONDLY]    = 1000 * 2;
 292 Dygraph.SHORT_SPACINGS[Dygraph.FIVE_SECONDLY]   = 1000 * 5;
 293 Dygraph.SHORT_SPACINGS[Dygraph.TEN_SECONDLY]    = 1000 * 10;
 294 Dygraph.SHORT_SPACINGS[Dygraph.THIRTY_SECONDLY] = 1000 * 30;
 295 Dygraph.SHORT_SPACINGS[Dygraph.MINUTELY]        = 1000 * 60;
 296 Dygraph.SHORT_SPACINGS[Dygraph.TWO_MINUTELY]    = 1000 * 60 * 2;
 297 Dygraph.SHORT_SPACINGS[Dygraph.FIVE_MINUTELY]   = 1000 * 60 * 5;
 298 Dygraph.SHORT_SPACINGS[Dygraph.TEN_MINUTELY]    = 1000 * 60 * 10;
 299 Dygraph.SHORT_SPACINGS[Dygraph.THIRTY_MINUTELY] = 1000 * 60 * 30;
 300 Dygraph.SHORT_SPACINGS[Dygraph.HOURLY]          = 1000 * 3600;
 301 Dygraph.SHORT_SPACINGS[Dygraph.TWO_HOURLY]      = 1000 * 3600 * 2;
 302 Dygraph.SHORT_SPACINGS[Dygraph.SIX_HOURLY]      = 1000 * 3600 * 6;
 303 Dygraph.SHORT_SPACINGS[Dygraph.DAILY]           = 1000 * 86400;
 304 Dygraph.SHORT_SPACINGS[Dygraph.WEEKLY]          = 1000 * 604800;
 305
 306 /**
 307  * This is a list of human-friendly values at which to show tick marks on a log
 308  * scale. It is k * 10^n, where k=1..9 and n=-39..+39, so:
 309  * ..., 1, 2, 3, 4, 5, ..., 9, 10, 20, 30, ..., 90, 100, 200, 300, ...
 310  * NOTE: this assumes that Dygraph.LOG_SCALE = 10.
 311  * @type {Array.<number>}
 312  */
 313 Dygraph.PREFERRED_LOG_TICK_VALUES = function() {
 314   var vals = [];
 315   for (var power = -39; power <= 39; power++) {
 316     var range = Math.pow(10, power);
 317     for (var mult = 1; mult <= 9; mult++) {
 318       var val = range * mult;
 319       vals.push(val);
 320     }
 321   }
 322   return vals;
 323 }();
 324
 325 /**
 326  * Determine the correct granularity of ticks on a date axis.
 327  *
 328  * @param {number} a Left edge of the chart (ms)
 329  * @param {number} b Right edge of the chart (ms)
 330  * @param {number} pixels Size of the chart in the relevant dimension (width).
 331  * @param {function(string):*} opts Function mapping from option name ->
 332  *     value.
 333  * @return {number} The appropriate axis granularity for this chart. See the
 334  *     enumeration of possible values in dygraph-tickers.js.
 335  */
 336 Dygraph.pickDateTickGranularity = function(a, b, pixels, opts) {
 337   var pixels_per_tick = /** @type{number} */(opts('pixelsPerLabel'));
 338   for (var i = 0; i < Dygraph.NUM_GRANULARITIES; i++) {
 339     var num_ticks = Dygraph.numDateTicks(a, b, i);
 340     if (pixels / num_ticks >= pixels_per_tick) {
 341       return i;
 342     }
 343   }
 344   return -1;
 345 };
 346
 347 /**
 348  * @param {number} start_time
 349  * @param {number} end_time
 350  * @param {number} granularity (one of the granularities enumerated above)
 351  * @return {number} Number of ticks that would result.
 352  */
 353 Dygraph.numDateTicks = function(start_time, end_time, granularity) {
 354   if (granularity < Dygraph.MONTHLY) {
 355     // Generate one tick mark for every fixed interval of time.
 356     var spacing = Dygraph.SHORT_SPACINGS[granularity];
 357     return Math.floor(0.5 + 1.0 * (end_time - start_time) / spacing);
 358   } else {
 359     var year_mod = 1;  // e.g. to only print one point every 10 years.
 360     var num_months = 12;
 361     if (granularity == Dygraph.QUARTERLY) num_months = 3;
 362     if (granularity == Dygraph.BIANNUAL) num_months = 2;
 363     if (granularity == Dygraph.ANNUAL) num_months = 1;
 364     if (granularity == Dygraph.DECADAL) { num_months = 1; year_mod = 10; }
 365     if (granularity == Dygraph.CENTENNIAL) { num_months = 1; year_mod = 100; }
 366
 367     var msInYear = 365.2524 * 24 * 3600 * 1000;
 368     var num_years = 1.0 * (end_time - start_time) / msInYear;
 369     return Math.floor(0.5 + 1.0 * num_years * num_months / year_mod);
 370   }
 371 };
 372
 373 /**
 374  * @param {number} start_time
 375  * @param {number} end_time
 376  * @param {number} granularity (one of the granularities enumerated above)
 377  * @param {function(string):*} opts Function mapping from option name -&gt; value.
 378  * @param {Dygraph=} dg
 379  * @return {!Dygraph.TickList}
 380  */
 381 Dygraph.getDateAxis = function(start_time, end_time, granularity, opts, dg) {
 382   var formatter = /** @type{AxisLabelFormatter} */(
 383       opts("axisLabelFormatter"));
 384   var ticks = [];
 385   var t;
 386
 387   if (granularity < Dygraph.MONTHLY) {
 388     // Generate one tick mark for every fixed interval of time.
 389     var spacing = Dygraph.SHORT_SPACINGS[granularity];
 390
 391     // Find a time less than start_time which occurs on a "nice" time boundary
 392     // for this granularity.
 393     var g = spacing / 1000;
 394     var d = new Date(start_time);
 395     d.setMilliseconds(0);
 396     var x;
 397     if (g <= 60) {  // seconds
 398       x = d.getSeconds(); d.setSeconds(x - x % g);
 399     } else {
 400       d.setSeconds(0);
 401       g /= 60;
 402       if (g <= 60) {  // minutes
 403         x = d.getMinutes(); d.setMinutes(x - x % g);
 404       } else {
 405         d.setMinutes(0);
 406         g /= 60;
 407
 408         if (g <= 24) {  // days
 409           x = d.getHours(); d.setHours(x - x % g);
 410         } else {
 411           d.setHours(0);
 412           g /= 24;
 413
 414           if (g == 7) {  // one week
 415             d.setDate(d.getDate() - d.getDay());
 416           }
 417         }
 418       }
 419     }
 420     start_time = d.getTime();
 421
 422     for (t = start_time; t <= end_time; t += spacing) {
 423       ticks.push({ v:t,
 424                    label: formatter(new Date(t), granularity, opts, dg)
 425                  });
 426     }
 427   } else {
 428     // Display a tick mark on the first of a set of months of each year.
 429     // Years get a tick mark iff y % year_mod == 0. This is useful for
 430     // displaying a tick mark once every 10 years, say, on long time scales.
 431     var months;
 432     var year_mod = 1;  // e.g. to only print one point every 10 years.
 433
 434     if (granularity == Dygraph.MONTHLY) {
 435       months = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ];
 436     } else if (granularity == Dygraph.QUARTERLY) {
 437       months = [ 0, 3, 6, 9 ];
 438     } else if (granularity == Dygraph.BIANNUAL) {
 439       months = [ 0, 6 ];
 440     } else if (granularity == Dygraph.ANNUAL) {
 441       months = [ 0 ];
 442     } else if (granularity == Dygraph.DECADAL) {
 443       months = [ 0 ];
 444       year_mod = 10;
 445     } else if (granularity == Dygraph.CENTENNIAL) {
 446       months = [ 0 ];
 447       year_mod = 100;
 448     } else {
 449       Dygraph.warn("Span of dates is too long");
 450     }
 451
 452     var start_year = new Date(start_time).getFullYear();
 453     var end_year   = new Date(end_time).getFullYear();
 454     var zeropad = Dygraph.zeropad;
 455     for (var i = start_year; i <= end_year; i++) {
 456       if (i % year_mod !== 0) continue;
 457       for (var j = 0; j < months.length; j++) {
 458         var date_str = i + "/" + zeropad(1 + months[j]) + "/01";
 459         t = Dygraph.dateStrToMillis(date_str);
 460         if (t < start_time || t > end_time) continue;
 461         ticks.push({ v:t,
 462                      label: formatter(new Date(t), granularity, opts, dg)
 463                    });
 464       }
 465     }
 466   }
 467
 468   return ticks;
 469 };
 470
 471 // These are set here so that this file can be included after dygraph.js.
 472 Dygraph.DEFAULT_ATTRS['axes']['x']['ticker'] = Dygraph.dateTicker;
 473 Dygraph.DEFAULT_ATTRS['axes']['y']['ticker'] = Dygraph.numericTicks;
 474 Dygraph.DEFAULT_ATTRS['axes']['y2']['ticker'] = Dygraph.numericTicks;