- Blog

By popular demand, you can now download your graph as a .gif file:

.eps is coming soon as well!

I know it doesn’t look like much has changed in the last month, but I’ve been working hard on a bunch of back-end stuff to make Plot-O-Matic run faster and more stably. This morning I flipped the switches to move Plot-O-Matic to its spiffy new digs on Amazon’s Elastic Compute Cloud. Hopefully you’ll notice a difference.

As part of the upgrade, I also increased the data backup frequency to every 10 minutes, so your data is a wee bit safer now.

Now that that’s all done, I’m back to adding new features and making existing features better. If there’s something you really want Plot-O-Matic to do, or some little (or big!) thing that bugs you, now’s the time to let me know!

Scott

You can now upload your data as comma, semi-colon or tab delimited files. What’s a delimiter, you ask? It’s the character that you use to separate data into columns. If you have data that looks like this:

then comma delimited data would look like this:

x,y,z
0,0,0
1,1,1
2,4,8
3,9,27
4,16,64

and the semi-colon delimited data would look like this:

x;y;z
0;0;0
1;1;1
2;4;8
3;9;27
4;16;64

Plot-O-Matic will automatically detect the what you are using as a delimiter. For more information, see the uploads help.

This was all precipitated by Wim, who reminded me that in Belgium (and lots of other places in the world, of course!), he uses the comma as a decimal separator and therefore uses semi-colon delimited files. (Thanks Wim!)

So, not only can you upload data with semi-colon delimited files, but the comma will work as a decimal separator in any numbers in Plot-O-Matic.

(more reading on data types in Plot-O-Matic)

Plot-O-Matic now has an “undo” button. Here’s how it works:

• Every time you save, change graphs, or create or delete something, a ‘save point’ is created.
• You can use the back/forward buttons to move between ‘save points’.
• You can see what ‘save point’ you’re at by looking at the address bar. It’s the part after the ’#’ sign, and will be something like save_1 or save_32.
• If you are using FireFox, then the history will be saved if you go to another page and then back.
• If you are using Internet Explorer, the history will be lost if you go to another page and then back. I’m working on fixing this.

Please note that this is not (yet!) a true undo: if you delete a graph or graph line or data column, you can’t undelete by hitting the back key.

The International Conference of Physics Students is presumably in full swing in London right now. One of the many perks of attending is a free upgrade to a Premium Plot-O-Matic account. So, welcome to Plot-O-Matic ICPS folks.

To get your upgrade

• Sign up for a free account
• While logged in, click on the ‘account’ link in the top-right corner of your screen
• Upgrade to Premium
• Enter the coupon code you got in your ICPS handbook

That’s it!

Have a great time at the conference, it sounds like a blast.

P.S. If you’re organizing a conference and want to be able to offer your attendees free Plot-O-Matic accounts, drop me a line at scott@plotomatic.com.

You can now do calculations on columns.

Calculating using other columns

As an example, let’s say you had two data columns (column A and column B) and wanted a third column to show the sum of A and B

Hover your mouse over third column’s type (It’s currently ‘Unknown’)

Now, click on ‘convert to formula column’. A window will pop up.

We want to add columns A and B, so type ‘col(A) + col(B)’ in the text box. Next, click on OK.

Done!

Filling in columns automatically using ‘row’

The first example showed you how to calculate using column data. You can also access the row number of a column. If, for example, you wanted a column with data like this:

You could fill it in automatically with a formula of ‘row * 10’:

For more on this, see Column Formulas Help in the Plot-O-Matic help section.

In four easy steps

Hover your mouse over the graph tab

Click on it

Edit the title

Click on OK (or hit the ‘enter’ key)

In case you haven’t noticed, I updated the logo with what is affectionately known as the “egg-o logo”. Purty, ain’t it?

You’ll notice that your graphs look quite a bit different now, and hopefully you’ll agree that it’s a change for the better. The text is cleaner, and everything is less fuzzy. Also, the axis labelling for date-time graphs is much nicer. Take a peek:

I’ve added the ability to download and share graph. There’s a help article called how to download and share graphs. You can go read the article if you want, but the gist of it is this:

Click on the graph tab. You’ll see something like this:

To download the graph, click on the ’.png’ link. (Other image types will be available soon).

To share the graph, check the ‘share this graph’ check box, and then click on the ‘save data and update graph’ button. The graph tab will now look like this:

The link (in this case http://www.plotomatic.com/graphs/graph_121_b498a88421a1821.png) will take you to the shared graph.

One final note: the shared graph will not be automatically updated every time you make a change to your graph. If you want to update your graph, click on the ‘update shared graph’ link in the graph tab.

You can now upload and download data to your plotomatic datasets. I’m not going to go into much detail in this post, as this screenshot basically says it all:

It’s very basic so far: you can upload and download .csv files. Uploaded files can contain column titles in the first row if you want. There’s help on uploading and downloading in the help section.

Try it out and let me know what you think!

Scott

If you tried curve fitting last week, you might have noticed that there’s no way to get the results from a curve fit to show up on your graph. I’ve just added a partial solution to this. When you do a curve fit now, a ‘note’ will be added to your graph which will have the results of your curve fit in it. (The partial part is that this note won’t be on the graph when you download or link to it. This will be fixed in the near future.)

In the curve fit blog post, we ended up with data that looked like this:

and a curve fit dialog that looked like this:

If you do a curvefit now, you should end up with a note on your graph that looks like this:

Hover the mouse over the note, and you’ll see that note can be edited, moved around and hidden:

Click and hold on the ‘drag’ button to move the text around. Click on the ‘hide’ button to hide the text (you can show it again by clicking on ‘show result on graph’ in the curve fit dialog).

Clicking on the text or on the ‘edit’ button will open the text for editing. Current, I’ve formatted this text using the Textile markup language, but this will be changing to something a bit more suited to mathematical markup in the near future.

If you start editing, the text will be:

y = \equation
\variables.{\var_name=\var_fitvalue+/-\var_fiterror}

Looks kind of complicated, eh?

Here’s what’s happening:

Anything with a ’\’ in front of it will be substituted for something else by Plotomatic. In this case, \equation will be replace with your equation. instead of y=\equation, you’ll see y=Ax**2+B.

The \variables substitution is a bit more complicated. The stuff inside the curly brackets will be repeated for every variable in the curve fit. So, if you had a curvefit with 3 variables,

\variables.{This is a variable}

would be replaced by

This is a variable
This is a variable
This is a variable

The other thing that’s happening is that there are variable dependent substitutions. The table below explains these

Text	Substitution
\var_name	the variable’s name
\var_fitvalue	The variable’s value after fitting
\var_fiterror	The error on the fit for that variable

So, the code \variables.{\var_name=\var_fitvalue+/-\var_fiterror} will be replaced by

A = 0.994414 +/- 0.008155

for the variable A and

B = 1.02976 +/- 0.147

for the variable B

That’s it for now. I’ll talk more about formatting your equation and making it look nice after I’ve got the notes showing up in graphs that you download or link to.

I’ve just added the ability to do curve fitting. To try it out, click on the ‘curve fit’ tab, select the line you want to do a curve fit to and click on ‘create a curve fit for this line’.

Here’s a quick example. Say I have data that looks like this:

x	y
0	0.9
1	2.3
2	5.1
3	9.8
4	17.0
5	25.5
6	37.1

It’s roughly quadratic, so I want to fit it with an equation like this: y = Ax² + B.

The equation has two variables: A and B. There should already be one variable made for you, so click on ‘create new variable’ to make a second. Now name the first A, and set its starting value to 1.0. Name the second B and set its starting value to 1.0 as well.

Enter the equation in the equation box like this:

y = A*x**2+B

For more information on equations, go to the curvefit equation help page.

You can leave everything else as is. To actually do the curve fit, click on the ‘save data and update graph button’. You should see the results of the curve fit in the preference form, something like this:

Scott

I’ve just pushed an update to the server that lets you plot dates and times. You’ll notice a few changes. First, each datacolumn has a ‘type’. Plotomatic does its best to detect the type of data that you are entering. The data types supported are numbers, times, dates and date/times. If you float your mouse over the type, you can set the type or ask Plotomatic to re-detect the data type.

There are some constraints on how you use this. You can’t, for example, plot date and numeric data on the same axis. Plotomatic will complain if you try. Also, I tried to detect as many date/time formats as I could, but you may have to experiment a bit before getting it right. Here’s a list of the formats supported:

Numeric
Integers	1, 45034 and -32
Decimal numbers	1.3, -45232.323 and 0.00023
Exponential notation	1.3E23, -0.33E-32
Dates
yyyy/mm/dd or yyyy-mm-dd	1999/03/21, 1945-11-23
dd/mm/yyyy or dd-mm-yyyy	21/03/1999, 23-11-1945
mmm dd, yyyy	Mar 14, 1945 or February 12, 1999
Times
hh:mm	12:23, 9:45 AM, 3:30 PM
hh:mm:ss	12:23:54, 9:45:32 AM
Date/Time
Any combination of the Date and Time formats above

Give it a shot and let me know what you think.