Category: Uncategorized

HOW TO USE BUZZER WITH PI

On By Ben Larson Ph.D.In UncategorizedLeave a comment

beside of PI and its accessory which is PI, memory card 8 gig class 10, HDMI cable, keyboard, Mouse, Monitor and Wi-Fi dongle or Ethernet cable.it is recommended to have other equipment that…

Source: HOW TO USE BUZZER WITH PI

R: Intro to Statistics – Central Tendency

On By Ben Larson Ph.D.In R, UncategorizedLeave a comment

Central Tendency

One of the primary purposes of statistics is to find a way to summarize data. To do so, we often look for numbers known as collectively as measurements of central tendency (mean, median,  mode).

Look at the list below. This is a list of weekly gas expenditures for two vehicles. Can you tell me if one is better than the other, or are they both about the same?

rCentral

How about if I show you this?

rCentral1

Using the average, you can clearly see car2 is more cost efficient. At approx $21 a week, that is a savings of $630 over the course of the 30 weeks in the chart. That is a big difference, and one that is easy to see. We can see this using one of the 3 main measures of central tendency – the arithmetic mean – popularly called the average.

Mean

The mean – more accurately the arithmetic mean – is calculated by adding up the elements  in a list and dividing by the number of elements in the list.

rCentral2.jpg

In R, finding a mean is simple. Just put the values you want to average into a vector (**note to make a vector in R: var  <-c(x,y,z)) We then put the vector through the function mean()

rCentral3

Median

The median means, simply enough, the middle of an ordered list. This is also easy to find using R. As you can see, you do not even need to sort the list numerically first. Just feed the vector to the function median()

rCentral4.jpg

Mode

This is the last of 3 main measure. Mode returns the most common value found in a list. In the list 2,3,2,4,2 – the mode is 2. Unfortunately R does not have a built in mode function, so for this, we will have build our own function.

For those familiar with functions in programming, this shouldn’t be too foreign of a concept. However, if you don’t understand functions yet, don’t fret. We will get to them soon enough. For now, just read over the code and see if you can figure any of it out for yourself.

rCentral5

 

 

 

Power Query: Pull data from a website into Excel

On By Ben Larson Ph.D.In excel, UncategorizedLeave a comment

For this tutorial, you will need to have Power Query installed. If you are running Office 2016, Power Query should already be available. For Excel 2010 and 2013, here is a link to the download: Power Query

Power Query makes pulling data from a website quick and easy. In this example we will be extracting data from the Wikipedia page “List of NCAA Men’s Division I Basketball champions“. Here is a link to the website: Link to Wikipedia Site

If you open up the Wikipedia page and scroll down a bit, you will see a table:  Championship games, by year, showing winners and losers, final scores and venues. This the table we will be extracting into Excel.

powerQuery-web.jpg

  1. Open up a new Excel workbook. Locate the Power Query Tab on the Ribbon Bar
  2. Select Web Page
  3. In the pop up window, copy and paste the URL to the Wikipedia Page
  4.  Click Ok

powerQuery-web1

5. Notice as you click through the list of tables on the left side of the screen, the tables             appear in the preview screen on the right.

6. Select Championship games, by year….

7. Click Load 

powerQuery-web2.jpg

Congratulations. You now have the table from the Web in an Excel sheet.

powerQuery-web3

 

 

Power Query: Merge Data Sets

On By Ben Larson Ph.D.In excel, Uncategorized3 Comments

For this tutorial, you will need to have Power Query installed. If you are running Office 2016, Power Query should already be available. For Excel 2010 and 2013, here is a link to the download: Power Query

Here is a link to the practice file for this Lesson: Data Cleaning Power Query

If you open the Excel file, you will see 3 sheets with 3 tables (Work Order, Vehicles, Prices). We want to populate a single sheet combining the three tables into one data set.

datacleanPowerQuery

Open up a New Excel Workbook (A new file. Do not try working from the practice file). From the Ribbon bar select Power Query > From File > From Excel

datacleanpowerquery1

Select the practice file: dataCleaningPQuery.xlsx and when the Navigator pops up, select Work Orders

datacleanpowerquery2

Select Load. Once the work order loads, repeat the process, this time loading Prices.

**Note if the Query Editor window pops up, just click Close and Load. We will be working in the Query Editor window later. 

datacleanpowerquery4

Now go to the sheet with the Work Order table on it. Power Query > Merge

datacleanpowerQuery6

A) The top drop down box should already be populated. If not, select Work Orders for top and then select Prices for the bottom.

B) Now highlight the Service Columns in both tables.

C) Leave the Join Kind at Left Outer.

A Left Outer Join works as seen below. The left table is displayed in full and the the right table adds data based on columns that match up against data in the left table.

datacleanPquery

Note the text below “The selection has matched 29 out of the first 29 rows.” This is because if you look at the two columns we selected, they both have matching text. It is through this matching that we are able to line up the two tables into one.

Click OK and the Query Editor window will pop up.

Select the dual arrow icon in the NewColumn header and deselect Service from the list.

datacleanpowerquery8

Right click the NewColumn and Rename it Price. Click on it and hold down the mouse button. Now drag it so that price sits in between Service and Mech.

Hit Close & Load and your new merged table should look like this:

datacleanpowerquery9

Ok, now to load the Vehicle sheet.

Power Query > From File > From Excel. Select excel practice file and select Vehicles. DO NOT HIT LOAD this time. Instead, select Edit.

datacleanpowerquery10

If you look at the original data set, the Lic Plate column in the Work Order sheet and Licence Plate in Vehicles are the two column we need to match up. Unfortunately, they currently do not match. In the second table, the licence plates are preceded by the letters Lic. We need to remove this.

Right click on the Licence Plate> Replace Values

datacleanpowerquery11

Type Lic  into Value to  Find and leave Replace with blank. **Note — the Value to Find is “Lic ” with a space after it. Make sure you add the space.

datacleanpowerquery12

Click OK, the Licence Plate column will remove the Lic. Click Close & Load

Now it is time to merge. Go back to the Work Order sheet and click Merge

Set the top table to Work Orders. Set the bottom to Vehicles. Highlight Lic Plates and Licence Plate columns. Set Join to Left Outer Join and click okay.

datacleanpowerquery13

Click the double arrows on the new column and un-check column 1.

Rename the new columns Make and Model. Highlight both column and move them in between Lic Plate and Service. Click Close&Load

datacleanpowerquery15

Congratulations. You have now successfully merged 3 tables into 1 using Power Query. Now you can go forth and analyze the data.