Method basic

src/danfojs-base/transformers/merge.ts:237–281

* The basic methos perform the underneath operation of generating * the merge dataframe; using the combination keys generated from * bothe left and right DataFrame * e.g df = { * key1: ["KO", "K0", "K3", "K4"], * Key2: ["K1", "K1", "K3", "K5"], * A: [1,2,3,4] * B: [3,4,5,6]

(keys: ArrayType1D, leftKeyDict: keyComb, rightKeyDict: keyComb)

   * @param rightKeyDict 
   */
  private basic(keys: ArrayType1D, leftKeyDict: keyComb, rightKeyDict: keyComb): ArrayType2D {
    const data = []
    for (let i=0; i < keys.length; i++) {
      const key = keys[i] as string
      
      if (utils.keyInObject(leftKeyDict, key)) {
        const leftRows = leftKeyDict[key].filters
        const leftCombValues = leftKeyDict[key].combValues

        for (let lIndex=0; lIndex < leftRows.length; lIndex++) {
          const leftRow = leftRows[lIndex]
          if (utils.keyInObject(rightKeyDict, key)) {
            const rightRows = rightKeyDict[key].filters
            for (let rIndex=0; rIndex < rightRows.length; rIndex++) {
              const rightRow = rightRows[rIndex]
              const combineData = leftCombValues.slice(0)
              combineData.push(...leftRow)
              combineData.push(...rightRow)
              data.push(combineData)
            }
          } else {
            const nanArray = Array(this.rightCol?.length).fill(NaN)
            const combineData = leftCombValues.slice(0)
            combineData.push(...leftRow)
            combineData.push(...nanArray)
            data.push(combineData)
          }
        }
      } else {
        const rightRows = rightKeyDict[key].filters
        const rightCombValues = rightKeyDict[key].combValues

        for (let i =0; i < rightRows.length; i++) {
          const rightRow = rightRows[i]
          const nanArray = Array(this.leftCol?.length).fill(NaN)
          const combineData = rightCombValues.slice(0)
          combineData.push(...nanArray)
          combineData.push(...rightRow)
          data.push(combineData)

        }
      }
    }
    return data
  }

  /**
   * Generate outer key from leftKeyDict and rightKeyDict