How to create a Supply & Demand style chart

Question

Here's an example of a basic Supply and Demand Graph:

The Vertical Axis is always Price
The Horizontal Axis is always Quantity
There should be two lines, one for the supply curve and one for the demand curve, both of which represent different quantities at a particular price.

Here's some sample data:

| P | Qty D | Qty S |
|---|-------|-------|
| 4 |    95 |    40 |
| 5 |    90 |    65 |
| 6 |    80 |    80 |
| 7 |    60 |    90 |
| 8 |    50 |   100 |
| 9 |    45 |   110 |

When I try to map this in Google sheets as a Line chart with two series, it keeps adding price as the X-axis because that's the shared variable between the two, but price needs to be on the y-axis.

Sample Output (axes backwards):

This forum is asking the same question, but the links are dead

KyleMit · Answer

The problem is that Google sheets requires a shared X-Axis for multiple series of data:

This is true even if you select Combo Chart which just allows you to select multiple chart styes.

Since the QtyS & QtyD do not need to share identical data, we need to create one big, shared Quantity scale that merges all possible values and can be used by both.

To create a range of values, you just need to wrap a range in curly braces {...}.  To flatten multiple columns, you can separate multiple ranges with a semicolon ;.  Then Unique will strip out duplicates and Sort will put the remaining values in numerical order.  So we can create a combined set of values like this:

=Sort(Unique({A2:A7;B2:B7}))

Now we'll map the applicable data-points from each set of data onto the master quantity list with either a VLookup or Index...Match.  If we don't get a value, we'll just skip it with IsError like this:

=IfError(Index(A:C,Match(E2,A:A,0),3),"")

Combined, this should take the data set from above and return a usable format like this:

| Qty | Demand | Supply |
|-----|--------|--------|
|  40 |        |      4 |
|  45 |      9 |        |
|  50 |      8 |        |
|  60 |      7 |        |
|  65 |        |      5 |
|  80 |      6 |      6 |
|  90 |      5 |      7 |
|  95 |      4 |        |
| 100 |        |      8 |
| 110 |        |      9 |

Now we can easily create a chart with multiple series of data:

How to create a Supply & Demand style chart

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