Dataframe (#576)

* initial dataframe commit * initial dataframe port of core app * rename variables for clarity * remove unused import * comment out unused code * fix array handling bug in crossfilter dimension creation * allow creation of empty dataframes * handle non-existent columns * handle non-existent columns * revise tests for new dataframe * comments for clarity * comments for clarity * generate bulk add placeholder with real gene names * fix bug in gene name adding * more dataframe unit tests * fix bug - subset from current world, not universe * put cut and pasted code into a single function * improve caching of crossfilter * remove cascading update bug from graph * more performance work * improve state handling for scatterplot * performance optimization of critical path * add column summarization * dataframe utils * add callOnceLazy * fix tests * minor updates found during review * fix misspelling * remove RESTv02 from function names * comment cleanup * cut/icut col parameter defaults to null * break up large test * improve tests and comments on dataframe at/has functions
2026-09-23 04:58:13 +08:00 · 2019-02-22 11:31:34 -08:00
parent 57c4e9ff33
commit 6b33315cbe
29 changed files with 1798 additions and 611 deletions
@@ -0,0 +1,465 @@
+import { IdentityInt32Index } from "./labelIndex";
+// weird cross-dependency that we should clean up someday...
+import { sort } from "../typedCrossfilter/sort";
+import { isTypedArray, isArrayOrTypedArray, callOnceLazy } from "./util";
+import { summarizeContinuous, summarizeCategorical } from "./summarize";
+
+/*
+Dataframe is an immutable 2D matrix similiar to Python Pandas Dataframe,
+but (currently) without all of the surrounding support functions.
+Data is stored in column-major layout, and each column is monomorphic.
+
+It supports:
+* Relatively efficient creation, cloning and subsetting ("cut")
+* Very efficient columnar access (eg, sum down a column), and access
+  to the underlying column arrays.
+* Data access by row/col offset or label.  Labels are reasonably well
+  optimized for both numeric lables and arbitrary (eg, sting) labels.
+
+It does not currently support:
+* Views on matrix subset - for currently known access patterns,
+  it is more effiicent to copy on subsetting, optimizing for access
+  speed over memory use.
+* JS iterators - they are too slow.  Use explicit iteration over
+  offest or labels.
+
+Important assumptions embedded in the API:
+* Columns are implicitly categorical if they are a JS Array and numeric
+  (aka continuous) if they are a TypedArray.
+
+There are three index types for row/col indexing:
+* IdentityInt32Index - noop index, where the index label is the offset.
+* KeyIndex - index arbitrary JS objects.
+* DenseInt32Index - integer indexing.  Optimization over KeyIndex as it uses
+  Int32Array as a back-map to offsets.  This means that the index array
+  must be sized to [minLabel, maxLabel), so this is only useful when the label
+  range is relatively close the underlying offset range [minOffset, maxOffset).
+
+All private functions/methods/fields are prefixed by '__', eg, __compile().
+Don't use them outside of this file.
+
+Simple example:
+
+  // default indexing is integer offset.
+  const df = Dataframe.create([2,2], [['a', 'b'], [0, 1]])
+  console.log(df.at(0,0));  // outputs: a
+  console.log(df.col(1).asArray());   // outputs: [0, 1]
+
+  // KeyIndex
+  const df = new Dataframe([1,2], [['a'], ['b']], null, new KeyIndex(['A', 'B']))
+  console.log(df.at(0, 'A')); // outputs: a
+  console.log(df.col('A').asArray(); // outputs: ['a']
+
+Performance tuning is primarily focused on columnar access patterns, which is the
+dominant pattern in cellxgene.
+*/
+
+/**
+Dataframe
+**/
+
+class Dataframe {
+  /**
+  Constructors & factories
+  **/
+
+  constructor(dims, columnarData, rowIndex = null, colIndex = null) {
+    /*
+    The base constructor is relatively hard to use - as an alternative,
+    see factory methods and clone/slice, below.
+
+    Parameters:
+      * dims - 2D array describing intendend dimensionality: [nRows,nCols].
+      * columnarData - JS array, nCols in length, containing array
+        or TypedArray of length nRows.
+      * rowIndex/colIndex - null (create default index using offsets as key),
+        or a caller-provided index.
+    All columns and indices must have appropriate dimensionality.
+    */
+    Dataframe.__errorChecks(dims, columnarData, rowIndex, colIndex);
+    const [nRows, nCols] = dims;
+    if (!rowIndex) {
+      rowIndex = new IdentityInt32Index(nRows);
+    }
+    if (!colIndex) {
+      colIndex = new IdentityInt32Index(nCols);
+    }
+
+    this.__columns = Array.from(columnarData);
+    this.dims = dims;
+    this.length = nRows; // convenience accessor for row dimension
+    this.rowIndex = rowIndex;
+    this.colIndex = colIndex;
+
+    this.__compile();
+  }
+
+  static __errorChecks(dims, columnarData) {
+    const [nRows, nCols] = dims;
+    if (nRows < 0 || nCols < 0) {
+      throw new RangeError("Dataframe dimensions must be positive");
+    }
+    if (!Array.isArray(columnarData)) {
+      throw new TypeError("Dataframe constructor requires array of columns");
+    }
+    if (!columnarData.every(c => isArrayOrTypedArray(c))) {
+      throw new TypeError("Dataframe columns must all be Array or TypedArray");
+    }
+    if (
+      nCols !== columnarData.length ||
+      !columnarData.every(c => c.length === nRows)
+    ) {
+      throw new RangeError(
+        "Dataframe dimension does not match column data shape"
+      );
+    }
+  }
+
+  __compile() {
+    /*
+    Compile data accessors for each column.
+
+    Each column accessor is a function which will lookup data by
+    index (ie, is equivalent to dataframe.get(row, col), where 'col'
+    is fixed.
+
+    In addition, each column accessor has several functions:
+
+    asArray() -- return the entire column as a native Array or TypedArray.
+      Crucially, this native array only supports label indexing.
+      Example:
+        const arr = df.col('a').asArray();
+
+    has(rlabel) -- return boolean indicating of the row label
+      is contained within the column.  Example:
+        const isInColumn = df.col('a').includes(99)
+      For the default offset indexing, this is identical to:
+        const isInColumn = (99 > 0) && (99 < df.nRows);
+
+    ihas(roffset) -- same as has(), but accepts a row offset
+      instead of a row label.
+
+    indexOf(value) -- return the label (not offset) of the first instance of
+      'value' in the column.  If you want the offset, just use the builtin JS
+      indexOf() function, available on both Array and TypedArray.
+
+    iget(offset) -- return the value at 'offset'
+
+    */
+    const { getOffset, getLabel } = this.rowIndex;
+    this.__columnsAccessor = this.__columns.map(column => {
+      const { length } = column;
+
+      /* get value by row label */
+      const get = function get(rlabel) {
+        return column[getOffset(rlabel)];
+      };
+
+      /* get value by row offset */
+      const iget = function iget(roffset) {
+        return column[roffset];
+      };
+
+      /* full column array access */
+      const asArray = function asArray() {
+        return column;
+      };
+
+      /* test for row label inclusion in column */
+      const has = function has(rlabel) {
+        const offset = getOffset(rlabel);
+        return offset >= 0 && offset < length;
+      };
+
+      const ihas = function ihas(offset) {
+        return offset >= 0 && offset < length;
+      };
+
+      /*
+      return first label (index) at which the value is found in this column,
+      or undefined if not found.
+
+      NOTE: not found return is DIFFERENT than the default Array.indexOf as
+      -1 is a plausible Dataframe row/col label.
+      */
+      const indexOf = function indexOf(value) {
+        const offset = column.indexOf(value);
+        if (offset === -1) {
+          return undefined;
+        }
+        return getLabel(offset);
+      };
+
+      /*
+      Summarize the column data. Lazy eval;
+      */
+      const summarize = callOnceLazy(() =>
+        isTypedArray(column)
+          ? summarizeContinuous(column)
+          : summarizeCategorical(column)
+      );
+
+      get.summarize = summarize;
+      get.asArray = asArray;
+      get.has = has;
+      get.ihas = ihas;
+      get.indexOf = indexOf;
+      get.iget = iget;
+      return get;
+    });
+  }
+
+  clone() {
+    return new this.constructor(
+      this.dims,
+      [...this.__columns],
+      this.rowIndex,
+      this.colIndex
+    );
+  }
+
+  static empty() {
+    return new Dataframe([0, 0], []);
+  }
+
+  static create(dims, columnarData) {
+    /*
+    Create a dataframe from raw columnar data.  All column arrays
+    must have the same length.   Identity indexing will be used.
+
+    Example:
+    const df = Dataframe.create([2,2], [new Uint32Array(2), new Float32Array(2)]);
+    */
+    return new Dataframe(dims, columnarData, null, null);
+  }
+
+  __cut(rowOffsets, colOffsets) {
+    const dims = [...this.dims];
+
+    const getSortedLabelAndOffsets = (offsets, index) => {
+      /*
+      Given offsets, return both offsets and associated lables,
+      sorted by offset.
+      */
+      if (!offsets) {
+        return [null, null];
+      }
+      const sortedOffsets = sort(offsets);
+      const sortedLabels = new Array(sortedOffsets.length);
+      for (let i = 0, l = sortedOffsets.length; i < l; i += 1) {
+        sortedLabels[i] = index.getLabel(sortedOffsets[i]);
+      }
+      return [sortedLabels, sortedOffsets];
+    };
+
+    let { colIndex } = this;
+    if (colOffsets) {
+      let colLabels;
+      [colLabels, colOffsets] = getSortedLabelAndOffsets(
+        colOffsets,
+        this.colIndex
+      );
+      dims[1] = colOffsets.length;
+      colIndex = this.colIndex.cut(colLabels);
+    }
+
+    let { rowIndex } = this;
+    if (rowOffsets) {
+      let rowLabels;
+      [rowLabels, rowOffsets] = getSortedLabelAndOffsets(
+        rowOffsets,
+        this.rowIndex
+      );
+      dims[0] = rowLabels.length;
+      rowIndex = this.rowIndex.cut(rowLabels);
+    }
+
+    /* cut columns */
+    let columns = this.__columns;
+    if (colOffsets) {
+      columns = new Array(colOffsets.length);
+      for (let i = 0, l = colOffsets.length; i < l; i += 1) {
+        columns[i] = this.__columns[colOffsets[i]];
+      }
+    }
+
+    /* cut rows */
+    if (rowOffsets) {
+      columns = columns.map(col => {
+        const newCol = new col.constructor(rowOffsets.length);
+        for (let i = 0, l = rowOffsets.length; i < l; i += 1) {
+          newCol[i] = col[rowOffsets[i]];
+        }
+        return newCol;
+      });
+    }
+    return new Dataframe(dims, columns, rowIndex, colIndex);
+  }
+
+  cutByList(rowLabels, colLabels = null) {
+    const toOffsets = (labels, index) => {
+      if (!labels) {
+        return null;
+      }
+      return labels.map(label => {
+        const off = index.getOffset(label);
+        if (off === undefined) {
+          throw new RangeError(`unknown label: ${label}`);
+        }
+        return off;
+      });
+    };
+
+    const rowOffsets = toOffsets(rowLabels, this.rowIndex);
+    const colOffsets = toOffsets(colLabels, this.colIndex);
+    return this.__cut(rowOffsets, colOffsets);
+  }
+
+  icutByList(rowOffsets, colOffsets = null) {
+    return this.__cut(rowOffsets, colOffsets);
+  }
+
+  icutByMask(rowMask, colMask = null) {
+    /*
+    Cut on row/column based upon a truthy/falsey array.
+    */
+    const [nRows, nCols] = this.dims;
+    if (
+      (rowMask && rowMask.length !== nRows) ||
+      (colMask && colMask.length !== nCols)
+    ) {
+      throw new RangeError("boolean arrays must match row/col dimensions");
+    }
+
+    /* convert masks to lists - method wastes space, but is fast */
+    const toList = (mask, maxSize) => {
+      if (!mask) {
+        return null;
+      }
+      const list = new Int32Array(maxSize);
+      let elems = 0;
+      for (let i = 0, l = mask.length; i < l; i += 1) {
+        if (mask[i]) {
+          list[elems] = i;
+          elems += 1;
+        }
+      }
+      return new Int32Array(list.buffer, 0, elems);
+    };
+    const rowOffsets = toList(rowMask, nRows);
+    const colOffsets = toList(colMask, nCols);
+    return this.__cut(rowOffsets, colOffsets);
+  }
+
+  /**
+  Data access with row/col.
+  **/
+
+  col(columnLabel) {
+    /*
+    Return accessor bound to a column.  Allows random row access
+    based upon the row indexing.  Returns undefined if the
+    columnLabel is not present in the dataframe.
+
+    Example for a dataframe with string labeled columns, and
+    default (offset) indices for rows (eg, [0, 'foo'])
+
+      const getValue = df.col('foo');
+      for (let r = 0; r < df.nRows; r += 1) {
+        console.log(r, getValue(r));
+      }
+
+    See __compile() for the functions available in a column accessor.
+    */
+    const coff = this.colIndex.getOffset(columnLabel);
+    return this.__columnsAccessor[coff];
+  }
+
+  icol(columnOffset) {
+    /*
+    Return column accessor by offset.
+    */
+    return this.__columnsAccessor[columnOffset];
+  }
+
+  at(r, c) {
+    /*
+    Access a single value, for a row/col label pair.
+
+    For performance reasons, there are no bounds or existance
+    checks on labels, and no defined behavior when these are supplied.
+    May return undefined, throw an Error, or do something else for
+    non-existant labels.  If you want predictable out-of-bounds
+    behavior, use has(), eg,
+
+    const myVal = df.has(r,l) ? df.at(r,l) : undefined;
+    */
+    const coff = this.colIndex.getOffset(c);
+    const roff = this.rowIndex.getOffset(r);
+    return this.__columns[coff][roff];
+  }
+
+  iat(r, c) {
+    /*
+    Access a single value, for a row/col offset (integer) position.
+
+    For performance reasons, there are no bounds checks on row/col offsets
+    or other well-defined behavior for out-of-bounds values.  If you want
+    well-defined bounds checking, use ihas(), eg,
+
+    const myVal = df.ihas(r, c) ? df.iat(r, c) : undefined;
+    */
+    return this.__columns[c][r];
+  }
+
+  has(r, c) {
+    /*
+    Test if row/col labels exist in the dataframe - returns true/false
+    */
+    const [nRows, nCols] = this.dims;
+    const coff = this.colIndex.getOffset(c);
+    const roff = this.rowIndex.getOffset(r);
+    return coff >= 0 && coff < nCols && roff >= 0 && roff < nRows;
+  }
+
+  ihas(r, c) {
+    /*
+    Test if row/col offset (integer) position exists in the
+    dataframe - returns true/false
+    */
+    const [nRows, nCols] = this.dims;
+    return c >= 0 && c < nCols && r >= 0 && r < nRows;
+  }
+
+  /****
+  Functional (map/reduce/etc) data access
+
+  XXX: not yet implemented, as there is no clear use case.   Can easily
+  add these as useful.
+  ****/
+
+  /*
+  Map & reduce of column or row
+
+  XXX TODO remainder of map/reduce functions:  mapCol, mapRow, reduceRow, ...
+  */
+  /* comment out until we have a use for this
+
+  reduceCol(clabel, callback, initialValue) {
+    const coff = this.colIndex.getOffset(clabel);
+    const column = this.__columns[coff];
+    let start = 0;
+    let acc = initialValue;
+    if (initialValue === undefined) {
+      acc = column[0];
+      start = 1;
+    }
+    for (let i = start, l = column.length; i < l; i += 1) {
+      acc = callback(acc, column[i]);
+    }
+    return acc;
+  }
+  */
+}
+
+export default Dataframe;