Computer Science 1000

Spreadsheets I

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Computers and Data suppose we ask a computer to remember a retail

transaction a list of 5 items the cost of each item the subtotal the tax associated the final total

how does the computer do this?

Socks $ 4.99Pants $ 65.99Shirt $ 47.99Tweed Suit Jacket $119.99Driving Gloves $ 28.99Subtotal $267.95Tax $ 13.40Total $281.35

Computers and Data computer memory (RAM) – a simplified version

your computer memory is like a massive set of storage “bins”

think of a post office with 8 billion mailboxes

each bin stores a byte of information each bin has a label

called its address each running program is given a subset of those bins, called its

address space

Computers and Data when your program wants to store data

it chooses a memory location that’s: a) large enough

e.g. if it’s storing a piece of text that is 20 characters, it must find a 20 byte piece of memory

b) currently unused we don’t want to overwrite existing

program information

the data is copied to that location in memory

the address of that memory is remembered

this is accomplished using a variable, in programming language speak

K

E

V

Computer Memory

name

Computers and Data when your program wants to

access data that it has stored it locates the appropriate spot in

memory using its remembered address

the data can be copied from that spot

perhaps to be used in a computation, or sent to an I/O device

K

E

V

Computer Memory

name

Computers and Data some points to consider:

the layout of the data in memory is usually not important to the program

as long as it can access the data it needs (by its memory address), that’s fine

from our previous example, perhaps the transaction items get stored at various locations in a program’s memory

the format of the data in memory is usually not important to the program

suppose the price of an item was $4,356.90 the computer will simply store this (in binary form) as the floating-

point number 4356.9

Computers and Data while layout and format might not be important to the

computer, those details are important to the user layout issues:

proximity creates cohesion – like items can be placed together, while unlike items can be distanced from each other – facilitating categorization (and hence, faster searching)

certain alignment of text facilitates easier reading aligning decimal places in numbers facilitates easy number comparison

format issues: certain formatting (currency: commas, dollar signs, two decimal places) are

familiar to us text formatting (bold, italic) allow us to highlight critical information (headers,

keywords, etc)

Computers and Data to summarize:

when dealing with information, layout and formatting of data can facilitate some key advantages for users, even if that information is not necessary for the data to be stored

there are a number of application programs designed to present information in a meaningful way to a person

browsers (markup languages – next week) spreadsheets (today!)

Spreadsheet a two-dimensional grid of data, that allows

relationships between items of data each grid location is called a cell each horizontal line of cells is called a row each vertical line of cells is called a column hence, each cell has a unique row/column identification

that differentiates it from the other cells

Example (Excel™)Cell

Example (Excel™)Row

Example (Excel™)Column

Spreadsheet – Software Microsoft Excel

the most widely used office software part of the Office software suite

OpenOffice Calc a free spreadsheet alternative part of the OpenOffice suite

LibreOffice Calc another free alternative part of the LibreOffice suite

many similarities (cell addressing, numbered rows, lettered columns) some differences (e.g. ; vs , ) for this course, we will use Microsoft Excel, as it is available in your

computer lab

Spreadsheet – Row Labeling each row in a spreadsheet has a label for most spreadsheet programs, the label is a number

first row labeled with 1 last row depends on the application and its version e.g. my Excel 2010 goes up to row 1048576

rows are often stated as “Row” plus their label e.g. one would refer to the highlighted row below as “Row 4”

Spreadsheet – Column Labeling each column in a spreadsheet has a label for most spreadsheet programs, the label is a letter

first column labeled with A columns are stated as “Column” plus their label

e.g. one would refer to the highlighted row below as “Column E”

Spreadsheet – Column Labeling what happens when we run out of letters?

e.g. what is the 27th column called?

the letters roll over, much like digits do first 26 columns: A – Z next 26 columns: AA-AZ next 26 columns: BA-BZ

Spreadsheet – Cell Labeling a cell typically belongs to one row and one column

this ignores merged cells, but we’ll ignore that for now

a cell’s label is the combination of its column and its row

the cell highlighted in black is A1 the cell highlighted in red is C3

Cell Data at it’s simplest level, a spreadsheet simply stores data

each cell holds a value to insert data into a spreadsheet

click on a cell (this will highlight it) type the data you want to store press Enter, or select another cell

Cell Data what types of data can a

spreadsheet hold? numbers text dates/times

each of these can be formatted in a particular way

e.g. numbers can be displayed as currency ($, two decimal places) or a percentage

dates can be displayed in different formats

Spreadsheet – Example insert the data from our

retail transaction into the spreadsheet

items in Column A prices in Column B (as a

simple number)

Socks $ 4.99Pants $ 65.99Shirt $ 47.99Tweed Suit Jacket $119.99Driving Gloves $ 28.99Subtotal $267.95Tax $ 13.40Total $281.35

solution: highlight Cell A1, type Socks, press Enter highlight Cell B1, type 4.99, press Enter repeat for next seven lines

Spreadsheets – Cell Dimensions in our last example, Tweed Suit Jacket and Driving

Gloves do not fit in their cells hence, part of the item name is hidden behind its price

we need to make the column wider to do this:

manually: place your cursor at right side of column label, and drag

automatically: select your column (click on column label), and choose Autofit Column Width from the Format dropdown

Manual Autofit

Spreadsheets – Cell Dimensions note that row dimensions can also be controlled, in

the same way as column dimensions for example, suppose we wanted to provide a bit of

separation between the SubTotal line and the items of purchase

manual: place mouse between row labels and drag autofit: same menu as before, but select Autofit

Row Height note that the automatic solution won’t work for this

example, as it won’t increase the height of the cell

Cell Formatting as mentioned, a formatting can be applied to a cell note that this does not affect the value being

stored, just the value that is displayed there are many possibilities for formatting

we will consider a few here text numbers

some others will be considered in your lab the best method for learning: try them out

Cell Formatting - Text formatting text in cells is much like formatting in a

word processor can control font, colour, background, alignment,

word wrap, etc process:

select cells you wish to format choose the appropriate control from the Ribbon

example: italicize the Subtotal label and amount, and bold the Total and amount

Cell Ranges the previous works, but is a bit inconvenient

select A6, italicize select B6, italicize what if Row 6 contained 25 cells that we wished to apply

this to?

Solution: Cell Range a collection of cells, highlighted at once any formatting or editing (e.g. delete) will be applied

across all cells in a range

Cell Ranges to select a range:

drag your cursor from the top-left cell of your desired range to the bottom-right

e.g. to select all cells from D2 to F7

Cell Ranges if a range is rectangular, it is denoted as topLeft :

bottomRight in previous example, selected range was D2:F7

note that multiple rectangular ranges can be selected at once

denoted as range1, range 2 e.g. D2:E6, G2:H5 to select multiple ranges, hold

down Ctrl button

Cell Ranges from previous example

we need to boldface the bottom two cells let’s use a Range to do this

select the range using drag method click the bold (B) button in the Font group

Cell Formatting – Numeric spreadsheets offer different formatting options for numbers

number of decimal places types (currency, %) and others

many of these options found in the Number group of the Home ribbon

if no formatting is specifically applied to the cell, then a general formatting is assumed

no trailing zeroes no commas or symbols

Cell Formatting – Numeric from previous example, numbers should be formatted as a

currency select the numbers (as a range) from the drop-down menu in the Number group of the Home ribbon,

select Currency

Cell Formatting – Numeric many other options for numeric formatting not shown in

Ribbon to see these, click the symbol beside the Number label in

the ribbon this dialog box gives detailed control over how a number is

displayed

Cells – Stored Value vs. Displayed Value recall previous comment that formatting and layout doesn’t

affect the value being stored we can see the value being stored by examining the formula

bar when a cell is highlighted the formula bar (labeled fx) is positioned directly above the sheet

as the following slide shows: text values are stored as is, with no bold/italic etc … numeric values are stored without any formatting Formula

Bar

Cells – Stored Value vs. Displayed Value why is this important?

the power of a spreadsheet lies in its ability to compute values based on data in other cells (we’ll see this soon)

the value used for computation is the stored value, not the displayed value

in example below, cell A1 has been formatted to show only one digit after the decimal point

if we were to multiply the value of cell A1 by 2, we would get 1.5, not 1.6

Inserting Data we’ve seen how to append rows of data to an

existing spreadsheet suppose we wish to add data somewhere other

than the end e.g. suppose we want to add another purchased item to

our list, or a set of headers

a couple of options select the entire table as a range, and drag the border

using your mouse insert a new row, by right clicking on the row to insert

above, and select Insert

Inserting Rows - Drag

Not a good option in this case – notice the taller rows

Inserting Rows – Right Click

Much better – the correct rows are still tall.

Inserting Rows in either case, we’re now free to add headers

we’ll apply cell shading, boldface font, and a larger font size, to make the headings really stand out

Font Size

Boldface

Cell Shade

Spreadsheets - Borders every cell has a light border surrounding it

called gridlines extra borders can be added via the borders drop-down to add extra borders:

select the range that you would like to border use the drop-down to select border:

placement (all, top, bottom, left, right) style (thick, thin, etc)

from our previous example: add a single border above subtotal add a single border above total add a double border below total

Adding Border above Subtotalother borders are added in similar manner

Spreadsheets - Borders if you wish to disable gridlines (to really see your borders),

uncheck Gridlines in View ribbon

Sorting Dataspreadsheets typically allow us to sort data this has many useful applications

class grades (scholarships)sports – points (awards, fantasy pools)

method:select range that you wish to sortclick the sort buttonselect the type of sort (ascending/descending)

Sorting Datawhat happened?

Excel’s sort assumes that your data has a header that is not to be sorted

solution (choose one): include the header in your rangechoose Custom Sort, and deselect the My Data

has headers option

Sorting Datacaution must be used when sortingconsider our transaction example

suppose I want to sort from cheapest to most expensive

Sorting Dataprevious is not correct

when we move the price, we must move the corresponding item

fortunately, Excel warns us when we are about to do this

we can avoid the warning by selecting the entire range that we wish to sort, and the column to sort on

choose Custom Sort, and choose your column to sort on