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General overview
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Caution: Use this tool carefully to avoid data loss or dataset corruption. |
The Analyst calculator is a powerful tool for data editing and calculation. The calculator includes tools for column creation and deletion, calculation tools with common functions, and data selection:
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You can drag a column from the column list and drop it into one of the expression boxes. Column expression will be correctly transformed into processing form. This behavior is implemented in the unique values list too. Predefined functions can be dragged and dropped into the calculation expression box. |
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# | Component | Description |
1 | List of columnsColumns | List of columns parameters available for expression construction. For inserting the expression you can drag the list item and drop it into one of the expression boxes or just double-click on the name and the column will be added to the expression with the cursor in the right form. |
2 | New | Opens the dialog for creating a new column in the dataset. |
Delete | Removes selected columns from the dataset | |
3 | Expression box for calculation | Insert expression for calculation. The calculation will be applied to selected records only or all records . Below the expression box are buttons with operands.if there is no selection. |
4 | Expression buttons | Click on the buttons to insert symbols in the expression box |
Clear | Clears expression field | |
5 | Functions | List of predefined functions which are possible to use in and constants which can be used in the expression boxes |
6 | Table view | The table view shows selected records - highlighted by yellow color. The table view includes a context menu with functions for manual selection and deselection of records. |
7 | Clear selection | Clears selected records |
8 | Calculate | Launch Start calculation |
9 | Describe column | Describe column opens and expands the Column description section. All unique values in the column are listed. This can be used to see all existing flag columns. Values are often used in a calculation or selection expression. Users can drag & drop or double-click the value. Basic statistics are displayed at the bottom of the Column description section. (see screenshot below) |
10 | Switch selection | Invert selection. Selected points are deselected and not selected points are selected. |
11 | Selected records only | Show/hide not selected unselected rows for better readability. |
12 | Save | Save changes |
13 | Close | Close calculator window |
14 | Add to selection | Manually select white (unselected) rows and add them to selection. Calculation will be applied only to selected rows. |
Remove from selection | Manually select yellow (selected) rows and remove them from selection. | |
Selected rows on the top | This option reorders table view and moves selected rows on the top. |
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Useful calculation expressions
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Open Calculator
Push "Select data" button
Select DIF in the column list and press "Describe column"
Double-click on the DIF column (will bring the column into the expression box), press "==" button, and double-click on "NaN" value in a unique value list. Final expression looks like this: col["DIF"] == NaN
Press "Apply" and close the window after the message informs you about the selection. Now you have selected all records with missing DIF value
In the expression combo-box choose a column for calculation (col["DIF"])
Type in calculation formula into expression box (col["GHI"] - col["DNI"] * sin(radians(sun_elevation)))
Press "Calculate" to launch the calculation. Calculation is applied only for selected records
Press "Save" to save your calculation into your dataset.
Functions
Below is description about all available functions and constants.
Function name | Description | Example |
NaN | A constant representing “Not a number”, used as an empty value or represents a gap. | col["DIF"] == NaN |
sin() | Calculate sine | sin(radians(sun_elevation)) |
cos() | Calculate cosine | cos(col[“DNI“]) |
arcsin() | Arc sine | arcsin(col[“DNI“]) |
arccos() | Arc cosine | arccos(col[“DNI“]) |
degrees() | Convert radians to degrees | degrees(col[“DNI“]) |
radians() | Convert degrees to radians | radians(sun_elevation) |
abs() | Calculate absolute value | abs(col[“GHI”]) |
power() | Calculate power to a number | power(col[“DNI”],2) |
round() | Round number to a specified number of decimal places | round(clear_sky_DNI - col[“DNI“],2) |
clear_sky_GHI | Calculated theoretical curve for GHI. Theoretical curves are not the same as model clear sky curves, theoretical curves are simplified. | clear_sky_GHI - col[“GHI“] |
clear_sky_DNI | Calculated theoretical curve for DNI. Theoretical curves are not the same as model clear sky curves, theoretical curves are simplified. | clear_sky_DNI - col[“DNI“] |
sun_elevation | Calculated sun elevation in degrees. | sun_elevation |
sun_aspect | Calculated sun aspect in degrees. | sun_aspect |
sun_azimuth | Calculated sun azimuth in degrees. | sun_azimuth |
solar_constant | A solar constant = 1367 W/m2 | solar_constant |
declination | Calculated declination in degrees. | declination |
ETR_normal | Calculated Normal Extraterrestrial Solar Irradiance. | ETR_normal |
ETR_horizontal | Calculated Horizontal Extraterrestrial Solar Irradiance. | ETR_horizontal |
air_mass | Calculated air mass | air_mass |
clearness_index_mod() | Global horizontal modified clearness index | clearness_index_mod(col["GHI"]) |
clearness_index_dni_mod() | Beam normal modified clearness index | clearness_index_mod(col["DNI"]) |
albedo() | Calculate albedo from GHI and RHI | albedo(col["GHI"], col["RHI"], minimal_sun_elevation=5) |
relative_difference() | Calculate relative difference, e.g. (GHI_1 - GHI_2) / GHI_1 *100 | relative_difference(col["GHI_1"],col["GHI_2"]) |
calculate_GHI() | Calculate GHI from DNI and DIF | calculate_GHI(col["DNI"],col["DIF"]) |
calculate_DNI() | Calculate DNI from GHI and DIF | calculate_DNI(col["GHI"],col["DIF"]) |
calculate_DIF() | Calculate DIF from DNI and GHI | calculate_DIF(col["GHI"],col["DNI"]) |
mod() | Calculate modulo | mod(col[“WD“],360) |