How windy is Wellington? – Using Power Query to gather wind data from web

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Let’s take a whirlwind trip to coolest little capital – Wellington. It is a windy place, so hold on to your hats and spreadsheets.

Almost everyone who spends more than 2 days in Wellington would agree that it is a windy place. But how windy is Welly? In this two part series, we will use Power Query, Excel charts and coffee to answer that question.

But, first let’s start with a joke.

What happens when you throw a boomerang in Frank Kitts Park?

You will have to buy another one, coz you are not getting that one back.

Extracting the wind data

In order to understand how windy Wellington is, we need to get average wind speeds by day for last several days. Let’s get the data for last 2+ years (ie from 1 Jan 2016 to 21 Feb 2018).

There are many places where you can collect latest wind data. But when it comes to historical wind data, surprisingly few resources are available. We can use The National Climate database – CliFlo, to gather wind data. But the interface is confusing and I could only locate gust speeds, rather than average wind speeds over time.

We can use wunderground.com to fetch weather data for up to 13 months at a time.

But we need data for almost 26 months.

Very simple, we can query wunderground twice (or thrice), once per each year.

The historical data query URL looks like this:

https://www.wunderground.com/history/airport/NZWN/2016/1/1/CustomHistory.html?dayend=31&monthend=12&yearend=2016&req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=

All we had to do is, change 2016 to 2017 & 2018 to get respective data.

The actual data set will be a web page. But we can use power query to extract the portion of page that contains weather information.

On to Power Query – Building our Weather Data Extractor

Note: This is a slightly advanced tutorial on PQ. If you are a beginner, start with Introduction to Power Query and work thru examples on PQ tag page before reading any more.

Getting data from the web – building URL in parts

Open Excel and go to Data > New Query > From Other Sources > Web

For Power BI, this would be Edit Queries > New Source > Web 

Switch to “Advanced” mode and enter the URL as parts like below. We will switch the 2016 part to parameters soon, so we could get data for any year easily.

In the navigation pane, select “Table 1” which is the weather table.

Set up a parameter for Year

How would we get data for 2017 or 2018? Simple, we use parameters. These are like variables which can be plugged in to any part of your Power Query process.

In Power Query Editor, go to Home > Manager Parameters > New Parameter and call it Year. Enter the default value as 2016.

Now, go back and edit the source settings for the query and replace 2016s with parameter Year.

Cleaning the weather table

Turns out the weather data table is not clean. Although there are 366 days in 2016 (leap year), Wunderground adds headers for each month. So we end up with 378 rows (excluding the header). Each header contains month name and repeat of all the column names. We can extract the month name & combine that with date and year parameter to create the date for each row.

Here is a quick illustration of what we need to do.

But first, rename the very first column

Notice the first column? It is called as 2016. This is ok if we are interested in just 1 year of data. But if we re-run this query with Parameter=2017, our column heading will change. If you have dabbled with Power Query a few times, you will quickly realize that PQ will get in to a nasty fit anytime column headers change and impact downstream steps.

Simple, we shall rename it as FirstCol.

When you apply the new name, PQ will write this M instruction.

#”Renamed Columns”= Table.RenameColumns(Data1,{{“2016”, “First col”}})

This is not a fool proof solution, as when we change parameter to 2017, there won’t be a 2016 column in that new table.

So, instead, we can ask PQ to rename first column of the table.

You can do this by:

  • Note: You need “Formula Bar”. Enable “Formula Bar” by clicking View > Formula bar. This way you can actually see all the M code PQ is cranking up whenever you perform some actions on your data.
  • Click on fx button on the formula bar to insert a step. Simply type = Table.RenameColumns(Data1,{{Table.ColumnNames(Data1){0}, “First col”}})
  • Press Enter
  • Bingo, you have renamed the first column of your query to “First col”. This has no reference to 2016 or any year, so it should work on any table you fetch from that weather data page.

Cleaning the weather data – steps

Just follow these steps to clean the weather data.

  1. Add a custom column called Month and write this formula = if Text.Length([First col]) > 2 then [First col] else null
  2. Select Month column and Fill Down (Transform > Fill >Down)
  3. Select First col and change its type to whole number. This will make all month names as Error
  4. Remove errors from First col (Right click on column header and choose Remove Errors)
  5. Add a custom column called Date with the formula = Text.From([First col])&”-“&[Month]&”-“&Year
  6. Change this column to date type.
  7. Keep only Temp. (°C)2, Wind (km/h), Wind (km/h)2, Wind (km/h)3, Events, Date columns and remove all other
  8. Rename first four columns to Avg. Temp, Wind Max, Avg. Wind, Wind Gust

At this stage we have one year of wind and temperature data for Wellington. Time to create getWeatherData() function.

Making getWeatherData function in Power Query

Now that we have a parameterized query, just right click on the query and choose “Convert to Function”

PQ will build the function that can take year as input and return a table of weather data for that year (provided Wunderground.com co-operates)

Now, we just need to run this function three times, once each for 2016, 2017 and 2018 to get all the data.

Go back to Excel

Save your queries, but don’t load them yet. If PQ prompts about data load, select “Connection only” and jump to Excel.

  • Create a table with 3 rows and type 2016, 2017 and 2018 in that. Call this table Years.
  • Load this table to Power Query (Data > From Table)
  • Go to Add Column > Invoke Custom Function and invoke getWeatherData function for each year.
  • Expand the weather data tables.
  • Done!

At this stage, we have data for all 3 years. You can add some data clean up steps if you want. But all the wind & temperature data is here for us to analyze and visualize.

Download Example Workbook

Click here to download the Wellington Wind workbook. As you can see, I have added few more steps in PQ to clean up the data and include a “Is it windy?” conditional column.

Please note that this workbook is designed in Excel 2016. It may not work in older versions of Power Query. You can replicate most of the steps. Try doing it so that you will learn more about Power Query.

In the next part – Wind in Wellington – few visualizations

In the next part of this tutorial, we will build some visualizations to understand how windy Wellington gets and what is the best time to enjoy the beautiful outdoors.

Stay tuned.

How are you using Power Query? Please post about your power query escapades in the comments section. Also tell me how you went about re-creating the steps in this tutorial. I am all ears.

Why there are no undercover cops in Wellington? Their cover was always getting blown. That is why.

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33 Responses to “Show Months & Years in Charts without Cluttering”

  1. eladberko says:

    Very CooOOOoool 🙂

  2. JP says:

    Would it work if I merely change the display format for the dates, or do they actually need to be retyped in that format (Nov, Dec, etc)?

    ps- it's only about 34 donuts per month, or slightly more than 1 per day. Yum!

  3. Jon Peltier says:

    To make it work automatically when you create a chart, delete the labels above the Year and Month columns, but keep the label above the Y data (Donuts). The blank cells tell Excel that the first row and first two columns (indicated by the blanks) are special, so it uses the first row for series names an the first two columns for X axis labels.
     
    This is better than the other kind of donut chart, but you'll soon be carrying a big donut around your midsection.

  4. Erin Smith says:

    First off, thank you Chandoo for being respectful and taking out the "Jesus" comment. Not that I'd threaten to kill you, or start world-wide riots, or make you go into hiding if you didn't (as OTHERS would; wink, wink, nudge, nudge)... I just really appreciate your respectulness and consideration; so thank you. I was meaning to write you about it, but when I came to your site you'd already made the edit... so again, thank you!

    Secondly, I wanna say I think there's an easier way to do what you are demonstrating. I've got a pivot chart with months of data and all I had to do was right-click the x axis and then select "format axis", under "Axis Options" there's a check-box that says "Multi-level Category Labels". The chart I was able to do this on was a pivotchart however so maybe it wouldn't be that easy for a non-pivotchart.

    Anyway, love the site. Keep up the good work. Thanks also for being so open about your success, it's very encouraging and motivating.

    God (aka Jesus) Bless. 🙂

  5. Terry Dukes says:

    Hi Chandoo - great site! Another option to save space is to simply rotate the orientation of the text by 90 degrees, so the dates read vertical rather than horizontal. However, I like the elegance of your solution also.

  6. Kien Leong says:

    Hey Chandoo -- Great tip. Only yesterday I was working through some strange behaviour with formatting dates in PivotCharts. Seems the axes never want to cooperate. This is a neat and elegant solution I hadn't thought of using. May need to abandon pivotcharts to use formulas like that, but if we use dynamic named ranges, no big sacrifice.

    BTW, whatever did you do to get your site blocked in China? Never heard of regime change by a grass-root spreadsheet movement. Maybe your ISP is hosting some problem sites. Chandoo.org is certainly worth it for me to fire up the VPN, but I'm sure you would lose a lot of other visitors from the middle kingdom.

  7. Kapil says:

    Chandoo ... pls help.. the link is blocked over here... pls can you put the regular link... 🙂

  8. Chandoo says:

    @JP... Excel Axis formatting is linked to cell formatting by default. So you can just have the dates which are formatted to look like months (mmm).

    @Erin: It was not my intention to mock anyone's faith or religion. I just used the word as it is quite common. I decided to remove it as I got 2 emails from readers requesting for the same.

    Also, the pivot charts take pivot table groupings by default, so you need not do any of the above while making charts from pivot tables.

    @Kein: I am not sure why Chinese authorities decided to block my site. I wish they would actually look at the content instead of blocking sites based on simple text matching rules.

    @Kapil: The file is mirrored here: http://chandoo.org/img/d/date-axis-months-years-trick.xls

  9. Prateek says:

    Cool, really cool...

  10. SS says:

    Nice one Chandoo,

    Also would like to mention abt useful method while creating dynamic charts.

    In any chart where in the months keep on adding - instead of changing the range for the chart every time we add a month, we can actually format the months as dates (probably 1st of every month) still keep the format as "mmm" AND while selecting the data, we can select a huge rows (date column) once and for all, and the chart adjusts automatically with the data that we entered. So next month when I enter Dec's data, I need not change the source data of the chart, however it automatically adjusts.

    Hope I made sense.!

    Regards,
    SS

  11. Tom says:

    Thanks, Chandoo! This is a great tip - one that I will definitely put to use. I typically have an axis with mmm yy format, aligned vertically, but this will definitely look a bit cleaner (except in cases where the chart is too small for the axis labels to be displayed horizontally, even without the mmm yy on one line). Thanks again!

    Tom

  12. Josh says:

    Chandoo,
    Thank you for the posts you are very diligent not to mention very helpful. I would like to know how to get the separation lines on the axis? For example your candy sales chart has longer lines separating east and west how do you format that?

    Thanks for being very awesome!
    -Josh

  13. Alvaro says:

    Hi Chandoo, we can look the formulas because there is a message:"Unsupported features".
    Could you send a diferent Link ?
    Thanks.

  14. Matt says:

    @SS But what if you've got formulas in the data block (i.e where you would enter static data for the month of december)? My chart now shows #N/A #N/A in the axis with no data for all future dates.

    Chandoo, I've got a dynamic range set up showing #N/A errors for future dates. The MMM-DD date format format in row works fine, but when I use YYYY and MMM in two rows, the axis shows #N/A #N/A for all future dates with no data. How would you go about keeping those future months hidden?

  15. Jon Peltier says:

    Matt -

    In order for the axis to automatically extend to the dates within the range and ignore #N/A at the end, you need a date-scale axis, and for this you need to use one column with the complete date, not two columns with year and month.

    If you want to use two columns, you need to generate Names in the worksheet which define ranges only as long as the number of months. I have a review of dynamic chart approaches in http://peltiertech.com/WordPress/dynamic-chart-review/ and a whole category on my blog at http://peltiertech.com/WordPress/category/dynamic-charts/. Chandoo also has examples of his own on this site.

  16. Ethan says:

    How do you make a dynamic chart out of this?
    I can't get the axis labels range right.
    I tried something like this:
    =OFFSET(REPORT!$H$10:$I$10;0;0;COUNTA(REPORT!$H$10:$I$100);1)

    Any idea?

  17. Jon Peltier says:

    Ethan -
     
    Your offset formula defines a range 1 row in size, but the technique here requires 2 rows. Your definition should end with
     
    ;2)
     
    instead of
     
    ;1)

  18. Ethan says:

    Thanks Jon,
    Got it working now

  19. Neal says:

    Great! Now, is there any way to do this directly in Powerpoint? I don't like having linked excel files, so I create the graphs right inside Powerpoint, any way to do this there? I tried and was unsuccessful.

    Thanks.

  20. Joe says:

    Cool tip Chandoo......thanks

  21. [...] extract year and month from dates to avoid a mess in our stock chart. Chandoo has a great post: Show Months & Years in Charts without ClutteringIn cell B2:=YEAR(D2)In cell B3:=IF(YEAR(D3)=YEAR(D2), "", YEAR(D3))Cell C2:=IF(TEXT(D2, [...]

  22. Bilal says:

    Hi there,
    I have got a data ranging for 3 years. I want to show a chart which shows Jan of 2011, 2012 and 2013 together side by side; then Feb11, Feb12 and Feb13 side by side, then Mar11, Mar12 and Mar13, and so on until December.
    Please help. Thanks.

  23. Down With This Sort Of Thing says:

    Hi there

    Very good solution this. I have another question on it, though. How do you format the X-axis with monthly gaps (ie, with labels "Jan 2012", "Apr", "Jul", "Oct", "Jan 2013", "Mar", etc), when you're dealing with a data series with weekly or daily data points? The Axis Options dialogue box doesn't appear to offer "Date axis" as an option under the "Axis Type" section.

    I've managed to do it in one case with weekly data by setting the interval between tick marks at 13 -- the approximate number of weeks in a quarter -- to get 3-month intervals. But this wouldn't work if I wanted to show 1-month intervals, or had a more detailed daily data series to work with.

  24. Herro says:

    Any luck getting the dates to work on a scatter graph? I'm only getting numbers. Works fine on line graphs though.

  25. Apoorve says:

    How can we do the vice versa? i.e. on the x-axis showing year on the level 1, and months on level 2.
    I wanted to build these kind of axis labels for 5 years, with year on top and months at the bottom, but it should form in such a way that the seperating lines should seperate the entire data set only at December of each year, and no lines in between any month.

  26. Carlos says:

    Like!!
    Three times already today I have used this website and saved a ton of work time in researching excel tricks.

    Suggestion: Why not have a "like" or "this article was useful to me" button. That way you can see what is most useful by your users and maybe generate more content based on those "likes".

    Just saying. Thanks again and you're doing a great job!

  27. Haj says:

    Thanks for the tip. However, I couldn't download your file. The link is broken.

  28. JeteMc says:

    Thank You for taking the time to post this tip. I hope that you have a blessed day.

  29. Tom says:

    The link does not work properly and I'm not sure how to actually get the graph to display like this, its frustrating me a tonne. I cant work out what to google either to find an answer elsewhere! 🙁

  30. parag says:

    Is this possible with waterfall chart. Data hereunder -

    Years Abbrevation Amt

    2020 BEG 2,006
    REV 1,950
    EMP 1,058
    DM (3,244)
    OOE 1,078
    OPMT 182
    AB (638)
    END 2,392
    2021 REV 8,534
    EMP 67
    DM (2,142)
    OOE (3,120)
    OPMT 510
    AB 1,008
    END 7,249

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