# Evaluate
**Evaluate**
Given an expression evaluates the expression string. If performed on the data frame row, it evaluates via passing the row as a dictionary. If performed on a single value, it expects an additional argument 'key' to be used in the expression. \
@param expr: The expression to evaluate. \
@param key: An optional 'key' if evaluated on a single value instead of a dictionary.
To perform arithmetic operations on columns, evaluate function is used. This function works on data type with 'Numeric' columns (Float or Integer).
{% hint style="info" %}
To perform arithmetic operations on columns, make sure the column's data type is set to '**Integer**' (Numeric) or '**Float**'. Additionally, column values should not contain **NULL** or **Empty** values.
{% endhint %}
### Example 1:
Note - This example demos the use of the 'dm: map evaluate' function using expression to calculate total VM CPU count.
Step 1: Create an empty **evaluate\_example\_1** using AIOps studio as shown in the below screenshot.
Step 2: Add the following pipeline code/commands into the above-created pipeline as shown in the below screenshot:
You can copy the below code into your pipeline and execute that in your environment.\
\
\&#xNAN;*`##### This pipeline creates a list of rows with vm_cpu_sockets along with vm_cpu_cores`* \
*`##### for virtual machines using AIOps studio.`*\
\
*`##### RDA function 'Evaluate' is used to demo this example that uses expression`*\
*`##### to calculate total CPU allocated to each virtual machine.`*\
\
*`@dm:empty`* \
*`--> @dm:addrow vm_cpu_sockets = 1 & vm_cpu_cores = 3 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_cpu_sockets = 2 & vm_cpu_cores = 8 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_cpu_sockets = 1 & vm_cpu_cores = 2 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_cpu_sockets = 2 & vm_cpu_cores = 4 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_cpu_sockets = 2 & vm_cpu_cores = 8 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_cpu_sockets = 1 & vm_cpu_cores = 2 & vm_id = 'vm1'`*\
*`--> @dm:map to = 'vm_cpu_total' & func = 'evaluate' & expr = 'vm_cpu_sockets * vm_cpu_cores'`*
Step 3: Click verify button to make sure syntax and pipeline code is correct (as shown below)
Step 4: Click execute button and execute the pipeline. RDA will execute the pipeline without any errors (as shown below)
Step 5: RDA uses the evaluate function to calculate 'vm\_cpu\_total' (using expression as shown in the pipeline code snippet) as shown in the below screenshot.
### Example 2:
Step 1: Create an empty **evaluate\_example\_2** using AIOps studio as shown in the below screenshot.
Note - In the below example, **vm\_disk\_size\_bytes** is a column that has disk capacity in bytes, using the '**evaluate**' function, create a new column '**vm\_disk\_size\_gb'** and convert the bytes into GB.
Step 2: Add the following pipeline code/commands into the above-created pipeline as shown in the below screenshot:
You can copy the below code into your pipeline and execute that in your environment.
using the '**evaluate**' function, create a new column '**vm\_disk\_size\_gb'** and convert the bytes into GB.\
\
\&#xNAN;*`##### This pipeline creates a list of rows with vm_disk_size_bytes column that has`*\
*`##### disk capacity in bytes. Pipeline uses 'evaluate' function and maps to new column`*\
*`##### and convert the data into 'vm_disk_size_gb'`*\
\
*`##### RDA function 'Evaluate' is used to demo this example that uses expression`*\
*`##### to calculate 'vm_disk_size_gb'`*\
\
*`@dm:empty`* \
*`--> @dm:addrow vm_disk_size_bytes = 10737418240 & vm_id = 'vm1'`*\
*`--> @dm:addrow vm_disk_size_bytes = 322122542 & vm_id = 'vm2'`*\
*`--> @dm:addrow vm_disk_size_bytes = 21474836480 & vm_id = 'vm3'`*\
*`--> @dm:addrow vm_disk_size_bytes = 322122542 & vm_id = 'vm4'`*\
*`--> @dm:addrow vm_disk_size_bytes = 53687091200 & vm_id = 'vm5'`*\
*`--> @dm:map from = 'vm_disk_size_bytes' & to = 'vm_disk_size_in_gb'`*\
*`--> @dm:map attr = 'vm_disk_size_gb' & func = 'evaluate' & expr = 'vm_disk_size_gb/1024 /1024 /1024 '`* \
Step 3: Click verify button to make sure syntax and pipeline code is correct (as shown below)
Step 4: Click execute button and execute the pipeline. RDA will execute the pipeline without any errors (as shown below)
Step 5: RDA uses the evaluate function to calculate '**vm\_disk\_size\_gb**' (using expression as shown in the pipeline code snippet) as shown in the below screenshot.
Similar to the above-provided examples, users can upload any files that require any mathematical calculation and use the 'evaluate' function/expression to print or store the data.
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