☰ Contents · Computing

Creating charts and graphs

Lessons 25 · 1 lessons · B. Boltayev, A. Azamatov, A. Asqarov, M. Sodiqov, G. Azamatova. Fundamentals of Informatics and Computer Technology, Grade 8. Second edition. “O‘zbekiston milliy ensiklopediyasi” State Scientific Publishing House, Tashkent, 2015
25

Creating charts and graphs

Textbook: pp. 107–113
GoalChooses a chart type to suit the data, knows the parts of a chart and builds a chart or scatter graph from a table.
New words
chart: a picture that shows the numbers of a table · diagrammacategory: the name of a data item, such as a subject or a class · toifalegend: the key that links each colour to its data series · afsonadata series: all markers of one colour, taken from one row or column · ma’lumotlar qatori
Explanation

A chart shows the numbers of a table as a picture, so data can be understood and compared faster. The type depends on the task: a pie chart shows the shares of a whole, a column chart (histogram) compares several groups, and a scatter or line graph shows how one quantity depends on another. The parts of a chart are the categories (names), values (numbers), data series, axes with their scale, legend, titles and data labels; a pie chart has no axes. The order of making one is: select the data block → Insert → Chart → choose a type and look → set the title, legend and labels → choose where to place it. A chart is linked to its table: if a number in a cell changes, the chart changes too. This works in Excel and also in the free LibreOffice Calc and Google Sheets; the buttons are in slightly different places.

Worked examples
Pie chart: a phone’s 64 GB of storage – apps 24, photos 16, video 16, other 8. The photos’ share is 16 · 100 : 64 = 25 per cent and the apps’ share is 24 · 100 : 64 = 37.5 per cent; we put the category and per cent labels on the sectors.
Scatter graph: we plot y = 3x for whole x from –5 to 5. Fill column A with step 1, write =3*A2 in B2 and copy down: y = –15, –12, ..., 12, 15 (11 points). Select both columns and choose the scatter type.
Class activity

“Class survey”: a group enters the class’s votes for favourite subjects in a table (no names), makes a pie chart and a column chart, and discusses which is better for comparing.

Practice
1
Which chart type is convenient for showing the shares of a whole?
2
A library has 40 books: fiction 18, science 10, dictionaries 8, other 4. What per cent are science books?
3
How many points are there for the graph of y = 3x with whole x from –5 to 5?
4
Why does a column chart need a legend?