COMPUTING AND DATA ANALYSIS WITH EXCEL. Managing Datasets

Transcription

1 COMPUTING AND DATA ANALYSIS WITH EXCEL Managing Datasets

2 Introduction In industry, the data that you need to analyse for trends, curve fitting or other purposes may come from other programs like C or C++ in ASCII or other format. You will not have time to manually type these into your excel spreadsheet. MS excel provides some inbuilt methods to import a wide variety of data into its worksheet. This is the focus of today s session.

3 Outline 1 Importing Data into Excel From ASCII text files, e.g. fixed width, CSV, etc From webpages Manipulating data Concatenating data Parsing and reformatting data Converting data to different unitswith CONVERT

4 Collecting and Cleaning Up Data Data from Text Files Excel is capable of reading different file formats including text files. To open a text file, simply follow the steps below: File Open. The Open dialog box is opened

5 Data from Text Files The Open dialog by default only displays excel files. To list text files (with.txt extension), select All Files next to File name

6 Data from Text Files Next, double click the file you want to open. The text import wizard is opened to assist with parsing the text (i.e. to ensure the data ends up in rows and columns in thespreadsheet).

7 Data from Text Files ur data is delimited by tab spaces so we will keep the default settings by licking next, next or finished at the first instance. ote: ou could use the excel function Convert to convert data to different

8 Data from Text Files

9 Importing data from a web page You ve found a web page containing usefuldata. How do you get the web data intoexcel? Follow these steps to import data into excel 2013 or 2016 from a web page: Select the DATA tab on your excel spreadsheet.

10 Importing data from a web page Next, from the Get External Data group on the ribbon, select From Web. A New Web Query window (a web browser) is displayed.

11 Importing data from a web page Type in the web address or URL into the address bar to go to the web page containing the data (e.g. Browseto the relevant page and click the import button.

12 Importing data from a web page A pop up import data window is displayed. You are next asked to indicate the destination or where you want your import data (existing or New worksheet?) and click OK.

13 Importing data from a web page Web data is then displayed often with redundant data that needs cleaning

14 Manipulatingdata oncatenation in Excel The CONCAT() function in Excel 2016 or CONCATENATE() in earlier versions of Excel joinstwo or more text strings into one text string. Note that the document you import into EXCELfrom other sources might often contain information in awkward forms. For example Figure 1 A B C D 1 First Surname Area Number Name Code 2 Ahmed Ibrahim Joe Mitchell Michelle Daley Fig1

15 Manipulatingdata You are asked to use the CONCAT() functionto produce figure 2 from original table in figure 1. A B 1 Full Name Telephone Number 2 Ahmed Ibrahim Joe Mitchell Michelle Daley Steps: Fig.2 1) Enter the Concatenation function in A9 as shown in fig. 3 below

16 Manipulating data The concatenation function Note that we use empty quotation signs to provide tab space between the first and surname (in the text2 textbox above). Use the concat() function to complete the telephone number in column B. This time youdo not need the empty quotations.

17 Manipulatingdata The concatenation function aving completed the first full name and corresponding telephone umber, use the autofill handle to achieve the final product below:

18 Manipulatingdata arsing and reformatting data Excel 2013 and 2016 provide means to parse cells so that data contained in one column could be split into separate cells. Example, the original data may show first and last name in one cell in column A. Parsing then allow the first and last names in separate columns, A and B respectively without having to type the data into each individual cell manually. Follow the steps below to split data in a single cell into separate cells by parsing.

19 Manipulatingdata Parsing Data Select the entire column [A] containing the combined data (i.e. First and last name). Click the Data tab and under the Data Tools group, click on Text to Columns. The Convert Text to Columns Wizard" window below will pop up. Accept the default Delimited or choose Fixed width if your data is. Click Next.

20 Parsing data n the next Convert Text to Columns Wizard wind, choose the ppropriate delimiter from Semicolon, Comma, Space or Other. emember to specify your delimiter if you choose Other. Leave verything else to the default setting and click Next.

21 Parsing data The last of the Convert Text to Columns Wizard window allows you to format your data. Leave it to the default General unless you want your date values to be displayed in a particular format e.g. dd/mm/yy or yy/mm/dd). Take a first view of your result in the Data Preview (see below).

22 Parsing data Click Finish to display your values in separate cells as below. Amend the headings to reflect the content of each column.

23 The Convert Function The excel Convert function allows you to convert data to different units. The Convert function takes three parameters namely, the value or cell address of the value to be converted, the current unit of the value and finally the unit to convert to. See illustration below:

24 Lab Exercise Level 1: i) Parsing, Concatenating and Converting between units of measure, import data from text files into excel Level 2: Import data from text files into excel 2016, clean or remove redundant or irrelevant data. from downloaded data from a web page Level 3: Import data from a website into excel 2016, calculate daily/weekly returns, find minimum and maximum, etc from the calculations.