Hi Keerthana,
As you have already created a calculated field with groups, its easy to form a pie chart, follow the below steps:
For ex: This is my calculative field that i'm using to show a pie chart.
IF [Profit]<0 THEN "No profit"
ELSEIF [Profit]<100 AND [Profit]>0 THEN "Low profit"
ELSEIF [Profit]>200 THEN "High Profit"
ELSE "Moderate profit"
END
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Select the marks shelf from automatic to pie.
Drop the field created in color shelf and the aggregation of measure in size shelf.
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Hope it helps.
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