# Problem with Map syntax **URL:** \ **Category:** Fluxlang\ **Created:** [April 5, 2022, 11:51pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538 "2022-04-05T23:51:46Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Patrick808](https://avatars.discourse-cdn.com/v4/letter/p/b487fb/32.png) [@Patrick808](https://community.influxdata.com/u/Patrick808)\ **Post date:** [April 5, 2022, 11:51pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/1 "2022-04-05T23:51:46Z")
I’m trying to do simple math on the results of a pivot and I am getting “null” values. Substituting in fixed integer or float values it works as expected, so I assume that I am not piping the values into the function, but I can’t figure out where I went wrong. ```auto from(bucket: "IotaHourly") |> range(start: v.timeRangeStart, stop: v.timeRangeStop) |> filter(fn: (r) => r["ct"] == "AC1" or r["ct"] == "AC2" or r["ct"] == "AC3" or r["ct"] == "PNL-Kitchen" or r["ct"] == "PNL-Laundry" or r["ct"] == "TeslaWC") |> drop(columns: ["device", "_measurement", "_start", "_stop", "_field"]) |> pivot(rowKey: ["_time"], columnKey: ["ct"], valueColumn: "_value") |> map(fn: (r) => ({r with House: r._AC1 + r.AC2 + r.AC3 + r["PNL-Kitchen"] + r["PNL-Lauandry"] - r.TeslaWC }))** ``` Any tips (and explanation) where I went wrong? Looking at the output as a table the input numbers all look good and it is clear that the output is “null”. Everything was taken from the [Documentation Example](https://docs.influxdata.com/influxdb/cloud/query-data/common-queries/multiple-fields-in-calculations/#full-example-query) ---
**Author:** ![Anaisdg](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/anaisdg/32/6401_2.png) [@Anaisdg](https://community.influxdata.com/u/Anaisdg)\ **Post date:** [April 6, 2022, 3:30pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/2 "2022-04-06T15:30:05Z")
Hello @Patrick808, I believe you’ll have to group your data before you pivot it if you want to create calculations across those different tags. ```auto from(bucket: "IotaHourly") |> range(start: v.timeRangeStart, stop: v.timeRangeStop) |> filter(fn: (r) => r["ct"] == "AC1" or r["ct"] == "AC2" or r["ct"] == "AC3" or r["ct"] == "PNL-Kitchen" or r["ct"] == "PNL-Laundry" or r["ct"] == "TeslaWC") |> drop(columns: ["device", "_measurement", "_start", "_stop", "_field"]) |> group() |> pivot(rowKey: ["_time"], columnKey: ["ct"], valueColumn: "_value") |> map(fn: (r) => ({r with House: r._AC1 + r.AC2 + r.AC3 + r["PNL-Kitchen"] + r["PNL-Lauandry"] - r.TeslaWC }))** ``` ---
**Author:** ![scott](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/scott/32/16492_2.png) [@scott](https://community.influxdata.com/u/scott)\ **Post date:** [April 6, 2022, 3:37pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/3 "2022-04-06T15:37:46Z")
@Patrick808 It’s because you have `null` values in your math operations. If any operands in a mathematic operation are null, the operation returns `null`. There are two things I can think of that will cause this: 1. You have points with null values (pre-pivot) 2. Your timestamps don’t perfectly align, so as a result of the pivot, some rows don’t have values for some of the columns used in your map operation. I suspect it’s probably #2. There are a few solutions: 1. Use `fill()` to fill each of the columns in the pivoted data. Pivoted data does make this process a little cumbersome since `fill()` can only fill one column at a time: 2. You can normalize the timestamps to a precision where points should all align. For example, if you’re seeing sub-second differences in timestamps between all the different fields, you can normalize the timestamps to the second. To do this, use [`truncateTimeColumn()`](https://docs.influxdata.com/flux/v0.x/stdlib/universe/truncatetimecolumn/) before you pivot the data: Truth be told, you may need to do both of these. If timestamps still don’t align after normalizing/truncating the time values, you will still have to fill all the `null` columns. ---
**Author:** ![Patrick808](https://avatars.discourse-cdn.com/v4/letter/p/b487fb/32.png) [@Patrick808](https://community.influxdata.com/u/Patrick808)\ **Post date:** [April 6, 2022, 4:48pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/4 "2022-04-06T16:48:01Z")
I don’t think either explanation checks out. This is what the table from the pivot shows: ![FluxPivotMap](https://us1.discourse-cdn.com/flex023/uploads/influxdata/original/2X/5/5c682fd0e8d7f67b2342d491b6ea524e69670000.jpeg) ---
**Author:** ![scott](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/scott/32/16492_2.png) [@scott](https://community.influxdata.com/u/scott)\ **Post date:** [April 6, 2022, 5:14pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/5 "2022-04-06T17:14:14Z")
Ah, I see the issue. You have an underscore (`_`) in front of `AC1` in your `map()` call. That column doesn’t exist in the data, so it’s returning null. Remove the underscore and you should be good to go. ---
**Author:** ![Patrick808](https://avatars.discourse-cdn.com/v4/letter/p/b487fb/32.png) [@Patrick808](https://community.influxdata.com/u/Patrick808)\ **Post date:** [April 6, 2022, 6:34pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/6 "2022-04-06T18:34:58Z")
Doh… Thanks. So much for checking seven times! ---
**Author:** ![scott](https://sea1.discourse-cdn.com/flex023/user_avatar/community.influxdata.com/scott/32/16492_2.png) [@scott](https://community.influxdata.com/u/scott)\ **Post date:** [April 6, 2022, 6:38pm UTC](https://community.influxdata.com/t/problem-with-map-syntax/24538/7 "2022-04-06T18:38:10Z")
No problem. Happy to help!