Power BI Blog: Labelling Growth on a Line Chart – Part 1

Welcome back to
this week’s edition of the Power BI blog series.  This week, we start
looking at a method of labelling growth on a chart.

Power BI visuals are an excellent tool when
it comes to telling stories with our data. 
When we are analysing quantitative data, we often need to compare
percentage differences.  The most common
example of this would probably be, “How much did the stock change today?”.  However, how do we highlight that percentage
change on a Power BI visual, e.g. on a  stock price Line chart?

Above, we have created a custom visual to
show cumulative profit, focussing on a specified interval.  We have created a label to display the growth
of cumulative profit and the current selection is from April to July.  We can change the interval shown, by  choosing an end month,  and then specifying  how many months to look back.  The visual will not only display a label showing
the growth, but it will also change colour automatically depending on whether the
growth is positive or negative!

We will be using the Financials  sample dataset in Power BI Desktop, and you can download our demonstration file
with this link. 

First, we prepare to create our visual by
making a copy of the Calendar table.

Create a copy of
Calendar

The figure used for demonstration here is a
cumulative measure of Profit from the sample dataset, which we created
using the following DAX formula:

To be able to select and compare different
periods on the visual without applying filters to the background Line chart, we
need to make an unconnected copy of the Calendar Table, which we’ve
named YearMonth Copy.  Here, we
are comparing values from different months, so we will be using Year and Month for matching and sorting.  InYearMonth Copy, we create a label Year Month, where:

and also an index YM
Index:

We have used the UNICHAR function to convert the month numbers to capital letters so that we can sort
the Year Month label.

We also create, using the same formula, a
calculated column Year Month in the original Calendar Table.

To be able to choose how many months we
want to look back, we create a Table Period Selection by clicking New
table and then entering in the Formula bar:

Thus, we have created the options one [1] to
12, and then we create a measure Period Length:

When we select three [3] months to look
back, the measure Period Length will be four [4], i.e. length of
the whole comparison period.

So far, we have created the options to choose
from, i.e. the month to analyse and the number of months to look back.  Next, we will define the assisting measures
for plotting.

That’s it for this week, next time we show
how to create the chart measures that we need.

Check back next week for more Power BI tips
and tricks!