Enter Data Tab

This spreadsheet-like view is the place to enter, edit, and inspect your data. You can paste in data from Excel, from Matlab's array editor, or from just about any other source of tabular data, including plain-text files with tab-separated values.

EnterData.png

Layout

The following aspects of the layout are predefined:

  • Each column corresponds to a single variable in your data, e.g., time, or dissolved oxygen concentration.
  • The first row, labeled "desc", is for descriptions and other comments regarding the data in the column below, e.g., "elapsed time in seconds", or "dissolved oxygen concentration in ppm". (This row is for humans; Formulize ignores it.)
  • The second row, labeled "var", is where you give names to your variables, e.g., "t", or "DO".
  • The remaining rows are for data, each row representing a set of measurements or values that are in some sense simultaneous, e.g., a time and an oxygen measurement taken at that time.

Partitioned data

If your data consists of discontinuous parts (e.g., data from two or more independent experiments or time series), indicate separations with an empty row. This keeps Formulize from attempting to smooth or differentiate across discontinuous data points.

Expressions

You can fill an entire column with values derived from values in other columns by entering a mathematical expression (preceded by an "=") anywhere in the column. For example, suppose you have values of x in column A and values of y in column B, and you enter =sin(x)+y somewhere in column C. For each non-empty row, sin(x)+y will be evaluated using the values of x and y in that row, and the result will be placed in that row of column C. Note that references must be made using variable names, not cell addresses. Any function found on the Building Blocks page can be used in a column-filling expression.

Dates, times, dollars, and percents

These can be entered using the following formats:
2/14/2011 (month/day/year)
2/14/2011 19:24:22 (month/day/year hour:minute:second)
$15.22
76.1%

Using labels

You can create columns containing up to 100 different labels (e.g., "beagle", "dachshund", "poodle"). In the special case where a column contains only "true"/"false" or "yes"/"no", those labels will be automatically converted into 1s and 0s. In all other cases, Formulize will convert each label into a Boolean variable with values of 1 and 0. For example, take the following data set:

year breed
1976 dachshund
1977 beagle
1978 poodle

Formulize treats the above as the following:

year breed_ dachshund breed_ beagle breed_ poodle
1976 1 0 0
1977 0 1 0
1978 0 0 1

Note that all of the values in a given column must be of the same type; labels and numeric values can't be mixed.

Variable names

Use short names, preferably single letters, to keep the resulting formulae concise. For example, use F instead of Force. To use numeric subscripts, just append the number to the variable name. For non-numeric subscripts, append an underscore followed by the desired subscript. Examples: R2 will display as R2; C_3po will display as C3po.