Making charts

KCL • CCH • Minor programme • AV1000 • Numerical and graphical analysis

AV1000
Fundamentals of the digital humanities
Making charts

Introduction
1. What charts are for
2. Types of charts
Creating a chart
Printing worksheets and charts

I. Introduction

A. What charts are for

Charting or graphing visualises data. It does not in itself constitute proof of an argument nor is it primarily factual, though it uses facts to produce representative images. Charting is rather a visually “rhetorical” device for presenting one's view of data in order to support an argument, or as a means of exploring data in order to discover useful patterns. It is a tool of interpretation, especially in the humanities.

Anything that can be counted can be graphed. Thus changes in a human or animal population over time or distribution of a particular word across a text are served as equally well as the fluctuations of profit and loss in a business. Conventionally charts have not appeared in the published work of most humanists. This may change, but meanwhile charting may be used quite effectively “behind the scenes” to help one think through a particular argument.

B. Types of charts

There are two locations for generating charts:

embedded within the worksheet, preferably in an unused area but anywhere and to whatever size you determine;
on a separate chart sheet within the same workbook

two ways of generating them:

with the Chart Wizard (on the toolbar)
from the Chart option under the Insert menu.

and a variety of kinds: area, bar, column, line, pie, scatter, 3-D, each with variants. You must decide which kind fits the data and your approach; Excel will do almost anything you ask, however foolish. Again, charts are rhetorical devices. Choose the kind that most effectively shows what you want to demonstrate.

II. Creating a chart

A. Acquiring the data

Before you can generate a chart, you need the data to be charted in the form of an Excel worksheet. Such a worksheet is provided here. It shows the levels of carbon monoxide pollution for the London borough of Hackney for 1998. To acquire the worksheet, hackney-co-1998.xls, click here, then save the file to your computer. Then open it up in Excel.

B. Selecting the data

The first task in the making of a chart is to select from the worksheet the data you wish charted. This is most easily done if the columns and/or rows are adjacent, but any set may be selected. In the sheet depicted here, for example, column A and column E have been selected. These contain, respectively, a series of dates (A) and the level of carbon monoxide pollution in Hackney, recorded for each date at 0400 hours (E). The intended chart will thus graph the level of pollution at the chosen hour against time.

To select adjacent data, highlight the first column, row or cell, hold down the shift key and highlight the last column, row or cell. Be sure not to include any blank rows or columns.

To select non-adjacent data:

Select the rows and columns individually from the sheet, as in the above image, using the mouse together with the Control key.
Copy the data one piece at a time from the original location to a new one, either an unused portion of the sheet or a new sheet within the same workbook. This is somewhat more work, but the selection can then be saved and manipulated without reference to the original.

C. Making an embedded chart

Select the data, as above.
Click on the Chart Wizard button in the toolbar, as above, or on Chart in the Insert menu, then On this sheet.
When the pointer changes to a cross-hair with a chart symbol, position it on your worksheet, then click and drag a rectangle where you wish the chart to appear.
You will then see a dialogue box with the cell references; confirm these, click on Next >.
Choose the type of chart, click on Next >. (Note: you will be able to change the chart-type later, so a wrong choice at this point is not fatal.)
Choose the sub-type of chart, click on Next >.
In the Chart Options dialogue box, illustrated in the adjacent image, click on each of the tabs in turn, enter the appropriate information and choose the options. The following are the most important for our purposes:
1. Titles. Chart title and titles for the X and Y axes.
2. Legend. If you have more than one data series, then a legend is useful; otherwise not.
Click on Next.
Finally choose whether you want the chart generated as a new sheet, or embedded in another Excel object, such as a spreadsheet.
Click on Finish. For the current example, this will yield the following embedded chart:

D. Changing the type of chart or resizing it

To change the type, first make sure the chart is selected as an object, then use the Chart Type button on the toolbar to select another type. As you will see by experimentation, some types do not suit particular kinds of data.
To move or resize an embedded chart, click outside the chart to deactivate it, then click on it once to select it as a graphic object. To move it, position the mouse pointer over it so that it changes into an arrow, then drag the chart to a new position. To resize the chart, position the mouse pointer over a selection handle, and drag. (The selection handles for an embedded chart are the solid black rectangles at the corners and at the middle of each side.)

E. Other formatting options

Explanatory text may be placed in a text box anywhere in the chart (and can be used with arrows to highlight details). Click on the Drawing button in the Standard toolbar;
click on the Text Box button on the Drawing toolbar and drag a rectangle on the chart.
Type in your text, then click anywhere on the chart and the text will appear in a text box that may be resized or moved with the mouse.
Fonts, patterns, text may be changed. Under the Format menu, select Cells, then to change font, size and/or style, use the Font tab; to change alignment (e.g. left, centre, right-justified), use the Alignment tab; fill-patterns and borders, the corresponding tabs.
Axes and grid-lines. To control the number and type of tick marks, and the range and intervals of a numeric axis in a chart, first double-click on the chart to select it, then double-click again on on the appropriate axis, then use the Scale tab. To add gridlines to a chart, use the Horizontal Gridlines tool in the Chart toolbar, or select the Gridlines option under the Insert menu.

III. Printing worksheets and charts

A. Setup for the worksheet

To set up your worksheet for printing,

Activate the worksheet
Click on Page Setup in the File menu
Choose the desired options in the Page Setup tabs
Click on OK.

The Page Setup options include:

Page tab. Orientation (portrait or landscape); Paper size (make sure it is A4); Starting page number; Reduction or enlargement scaling: the Adjust To option, to scale the result to a stated percentage, or the Fit To option, to determine the number of pages wide and tall that will be used.
Margins tab
Header/footer tab. The default is a header with a centred filename, and a footer with the word “Page” followed by the page number, centred. To replace these defaults, click on the Custom Header or Custom Footer button, following the instructions.
Sheet tab, where you specify whether you wish to print cell gridlines, and row and column headings.

B. Setup for the chart

To set up a chart for printing:

Activate the chart sheet (or, for an embedded chart on its own, first activate it by double-clicking).
Click on Page Setup in the File menu.
Choose the desired options in the Page Setup tabs.
Click on OK.

Special setup options for printing charts. By default charts print in landscape orientation and fill the page. You can alter this by choosing Page Setup on the File menu. Select Page tab to change the orientation. Use the Chart tab to alter the area of page that the chart fills. Charts default to colour when on the screen. Change segments/bars to patterns if you wish.

C. Printing

Click on Print in the File menu, then click on Printer setup to ensure that you have the right printer (see relevant Computing Centre documentation), then click on OK.
In the Print dialogue box, choose range (either cells selected with the mouse, or active sheet, or embedded chart, or certain pages.
Click on Print Preview in the Print dialogue box to check what it will look like (clicking on Zoom if necessary to see the details), the click either on Page Setup or on Close, or on Print.
Finally, from the Print dialogue box (accessed via the File menu, or Print Preview), click on OK to print.

revised January 2008

AV1000 Fundamentals of the digital humanities Making charts