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High trade is back with another part
script video in today's video we're
going to be revisiting debugging in
pinescript so today's video is going to
be a bit of a recap on the previous
debugging video but I still think you'll
find it extremely valuable so stick
around even if you watched the previous
video we're going to cover some new
things that I didn't cover in the
previous video and the script I'm going
to show you today is really really cool
it's an extremely valuable tool so a
couple of weeks ago I released a video
on my channel exploring various methods
for debugging your scripts and one of
these subscribers to my mailing list
sent me an email thank you Justin making
me aware of this really incredibly
valuable tool created by a plan script
coder who goes by the name he who must
not be named and obviously a Harry
Potter fan and he's written this script
that creates a logging feature so what
you see down here is a print log and
this is printing text onto my screen
much like the pinescript editor does
down here now if you haven't watched my
previous video on debugging I highly
recommend it because we do cover some
interesting and useful techniques in
that video as well but in this video I'm
showing you a much quicker way to go
about debugging things such as for loops
and using this new script that Justin
sent me or made me aware of we can now
much more easily debug things like for
Loops now before we begin I want to
address something that I said
incorrectly in the previous debugging
video I mentioned how it wasn't possible
to plot data onto the chart without it
showing up in the status line so this is
the status lineup here and I mentioned
that if you want to display things in
the data window here you have to plot
the numbers onto your chart with a title
but the plot will show up on your status
line which is annoying when you have a
lot of plots because these status line
numbers can plot right off your chart
well a subscriber to the channel waldus
I hope I pronounced that correctly made
me aware of this feature that I somehow
missed last year it's been in PostScript
for a year so I apologize for that I had
I some now missed this these release
notes from July last year where you can
actually specify where you want your
plots to display which is really cool so
let's just quickly cover this before we
move on because this is uh important on
the subject of debugging so let's say we
want to display our plots everywhere
except on the status line so now we can
use this new display.all minus the
display dot status line and this will
display the plots information every
everywhere except in the scripts status
line which is amazing so let's go do
this really quick let's open up the
source code if you're not familiar with
this script this is the script I worked
with in the previous lesson where I
introduced you guys to a brand new
feature of panscript called Methods so
go and check out how to use methods in
pinescript that video there'll be a link
in the top right here somewhere to that
video If you haven't seen it but the
script we used for today's lesson is not
important you can use any of your
scripts and code along if you want to
but anyway let's scroll up to where I
plot my information let's say we want to
see this data in the data window but we
don't want it drawing onto our chart
which in this case we don't because this
is drawing EMA values from different
markets and we want to see these EMA
values in the data window but we don't
want them plotting onto our price chart
so we can now use the new display equals
if I paste that code in there I copy
that and paste it on the rest of these
plots save my code this is the first
time I'm doing this I hope it works
there we go it's no longer drawing in
the status window so that's how we plot
data onto the chart without it
displaying in the status line but also
displaying in the data window if we only
want the data to display in the data
Windows such as in this case where we
have these EMAs we don't want them
plotting on our chart we don't want them
plotting into the status line but we do
want them plotting here to achieve that
we can change this to display equals
display dot data window and now if I
copy this and paste it down here save my
script these plots should disappear from
here and here but still remain in the
data window there we go amazing thank
you so much welders for making me making
me aware of this feature I'll be using
this a lot in the future for sure one
final thing I also want to mention
before we move on is that when you're
debugging scripts you can also use alert
functionality so just add alerts to your
script that send a string either to your
email or just in the alert window and
then you can actually copy and paste
that string if you need to do something
with the data outside of trading View
and finally one other thing you can do
that I forgot to mention in the previous
debugging video is export your chart
data to an Excel spreadsheet that will
include all of your plot values for each
candle now this feature is only
available for premium subscribers to
trading views platform but if you open
up this menu here and come down to
export chart data and click export there
you go you have an Excel spreadsheet
with all of our different EMA values
this is another tool we can use for
debugging what our script is doing on
each candle so with all that out of the
way let's get to the core of today's
lesson where I will introduce you to
this new logging library that was
created by he who must not be named so
here is the published script on
tradingview leave a link below in the
video description to this script it's
really easy to use you can see down here
that it's got several different levels
for each message so you have just
general info you have warnings errors
fatal errors there's also trace and to
use this script is really really easy we
just need to copy this code here jump
into our script and then I like to do
this at the top of my script you don't
have to you can paste this in anywhere
but I recommend doing it at the top of
your script just so you know
uh what libraries your script is working
with now I've covered libraries before
on the channel but not for quite some
time so I'll quickly explain what we're
doing here we're importing he who must
not be names logger library and the
version is one now he's updated the
script to version two so I'll change
that one to two and he's giving this
Library an alias of L that's not a one
that looks like a one but it's Ashley L
short for logger so I'll just change
this to log real quick so it's a little
bit easier to read and then he's
creating a VAR persistent variable
called logger and this logger is set to
log Library Alias dot logger type dot
new so we're creating a new logger type
and then this logger type has some
methods included in it the first one is
init so we need to call this before we
do anything with this logger and this
will initialize our logo window that
we'll draw down here in the bottom right
and we're good to go so before we start
logging things onto the chart I'll just
go over the different parameters we have
to work with with this script or Library
so the first parameter here is position
this is where to draw the table or the
log they may have page size so that's
how many strings or lines of text draw
in this table then we have Max entries
that's the maximum number of entries we
can have in our logger then we have page
number I'll go over what that is once
we're logging things onto the chart then
we have text size text color show only
last means do you want to display the
logger only if we're on the final bar
about chart then we have minimum level
so this specifies the minimum level of
log to show on our chart so you can see
here in this example we're setting the
minimum level to debug so the logo will
only show messages that have a priority
of debug or higher so if we go back to
the page here we have Trace debug info
warn error and fatal so if we set the
minimum level to debug then we're not
going to see any messages that were
using the trace method we're only going
to see these ones and if I set it to
infos the minimum level then we'd only
see info and down so that one's pretty
self-explanatory then we have real time
which means is the logo being drawn on a
real-time bar or not this should be set
to true if we're dealing with an
indicator like in our case and it should
be set to false if you're working with a
strategy script and these final two
parameters here we don't need to touch
these will be created by the library
script when we call them our new
function here or method so let me get
rid of this for now and let me show you
how to log something so I'll just right
here test log
logo Dot and now when you import a
library and you use the dot notation so
you write out your type here and then at
Full Stop control space this gives you
the list of methods we have to work with
and there aren't that many it's a really
nice lean efficient Library script it's
no wonder that he who must not be named
is in the Pines script is Hall of Fame
he's a great scripter right it's really
clean really efficient code that is
really powerful now for some reason it
doesn't list the different methods here
we have for actually logging so let me
copy this and paste this in here and
I'll save my script let's have a look at
what happens down here there we go we're
getting some test logs drawing now for
the most part I doubt you're going to
need to use all of these different Trace
levels it's a great feature to have most
integrated development environments most
advanced scripting environments will
have these different levels to work with
I imagine that's why the author included
all of these but you don't need to use
them all you could just use info if you
wanted to or whichever one you find
easiest to read color otherwise so if I
get these get rid of these and I just
say this is a test log save my code now
you can see this message down here so
the First Column here this first number
is the index of the log string so it'll
start from zero and count upwards from
there the second number here is your bar
index the bar index to this table is
drawing on or this log message was made
on then we have the date and time if
you're on a lower time frame so if we go
down to a one hour chart it will also
show the bar time the open time of the
bar that we're on and then we have our
Trace level here and then the message
the string that we want to write onto
the chart so you can already see just
how powerful this is with four lines of
code we are drawing whatever text we
want onto the chart from anywhere in our
script we could be using this function
inside our for Loop to print out what
our for Loop's doing we could have it
inside a method a custom function inside
if statements and conditional statements
it's a really versatile and Powerful
feature to have in your scripts
especially complex scripts that have a
lot of moving parts and you want to
track what your script is doing and
ensure that it's doing what you intend
it to do and if it's not you can use
this logo to isolate the problem and
reverse engineer what the bug is so
before we continue let's try something
really quickly Let's uh log
logo.info bar index equals uh actually
we already know the buyer index on the
logger let's say bar open equals and now
we still need to use the string.to
string Library method to convert numbers
into text when when using this logger so
keep that in mind now when I save this
code let's have a look at what the
logger does so what's happening here is
the logger is only running on the last
bar on our chart on the current
real-time bar or the final historical
bar if the market is closed and so we're
only printing One log to the logger but
if I change this parameter here the show
only last equals false now we're not
using the logger only on the final bar
now chart if I save my code now with
this parameter set to false this logger
dot info method will be called on every
bar on my chart and so when I save my
code now we should be getting a fully
populated logger array full of text from
every bar on my chart there we go so by
default we have 10 is our page size so I
can change that if I want to let me
change this to page size equals 20. now
we should have 20 messages drawing into
our logo like so counting from 0 all the
way to 19. now the logo will show the
most recent message that went in first
so 0 will be the most recent bar open if
you want to see a few bars back you can
specify the page number so if I set page
number equals 10. now we'll be
displaying the logger from 10 pages ago
so 200 bars ago until the 219th bar so
if you're debugging a bar you know 200
bars ago that's a count back 200 bars
200 if I put a vertical line there and I
hover my mouse over this bar you can see
the open price there zero six two four
two zero six two four two so this is how
you can debug information in the past so
if your script's doing something funky
200 bars ago you can just do some quick
math to figure out how many pages back
you need to go with this logger and you
can see what your script was doing then
so just a couple more things before I
wrap up this lesson let's demonstrate
how to display an error message so let's
say our script let's say this EMA array
should have seven elements in it and if
it doesn't we want to be notified that
there's a problem this is just an
arbitrary example but let's say that if
EMA array dot size is not equal to 7
then we want to print an error
that says EMA size not equals seven size
equals and then I can copy that into
here save my code and now we'll be
getting an error message
um on every bar on our chart because
this if statement will be true on every
bar in our chart but if it wasn't then
we'd get our message in here so let's
say and bar state DOT is last and let's
add in a couple of uh regular info
messages test info
save my code let me get also get rid of
these two parameters here and now you
can see that on the last bar in our
chart we got an error message drawing
and you can see these two bar indexes
are the same so we're drawing test info
or logging text info on every bar in our
chart but if there's an error on the
last bar on our chart that also draws
into the log and yeah hopefully you can
see how powerful and useful this feature
is a couple more things let's do a debug
message so let's come down to our for
Loop so inside this for Loop let's say
we want to check what this for Loops
doing so first of all let's get the I
index from our first for Loop so I can
say I plus string dot two string I
and then let's also get the J index of
our second for Loop so J plus string dot
two string J
um and I'll change this to debug just to
demonstrate the different levels and
then I'm going to split this onto a new
line here
and I'll say Swap and let's just put in
some values here let's say we're
swapping I with the element at J now
this for Loop if you're not aware is
sorting our array so we need two for
Loops to cycle through all of the
elements in our array and swap whichever
ones are not if we're sorting in
ascending order we want to swap all the
elements so that the smallest values are
at the top and the largest values are at
the bottom so here I can say we are
swapping Source array dot get whoops
I dot ticker with
Source array dot get
J dot ticker and now I need to move this
debug message above the part where our
script actually swaps these elements
otherwise this information will be
incorrect so before we swap the elements
we log this to our logger so now if I
save my code this should compile there
we go and now the debug message isn't
displaying here so I think I might need
to change minimum
level equals trace and there we go so by
default the debug message level is
hidden so you need to set minimum level
to trace if you want to see all of the
different log levels and now we can see
what our for Loop is doing um let me get
rid of show only last because right now
this is logging every for Loop for all
the bars on our chart and this looks a
bit messy so let's just see what it's
doing on the final bar on our chart
let's get rid of that let's also add in
some EMA values here so that we can
actually see what values are getting
swapped around so I'll put in Brackets
here string dot two string
Source array I dot EMA value with and
then let's swap this onto a new line and
close that off and then add on this and
I'll just copy this code here and change
this to J
save my code and now we should be
getting less information because we're
only debugging the final burnout chart
and we're getting the EMA values as well
now we're getting a lot of decimal
places too I'm not going to show you how
to format strings in today's lesson
because I've covered that in previous
lessons and it's not important for today
but anyway you can now see that the for
loop I index 0 and the for Loop J index
3 has swapped euro dollar with this EMA
value here with New Zealand dollar and
this is a lower number so it's swapped
the position in the array of euro dollar
1.06 as the EMA value with a smaller EMA
value and has done that for all of the
elements in our for Loop and so our for
Loop was doing something we didn't want
it to we could read this text here and
see what's going on anyway I'm trying to
keep this video short because this isn't
exactly rocket science you can go and
play around with the script yourself
it's very easy to use as you can see
only three lines in order to get it into
your script and then once it's in your
script you can just use the logo.info or
whatever other level you want to write
write some debug text and see what's
going on under the hood of your script
so I hope you found this video helpful
and valuable and interesting if you did
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subscribed thank you so much for being
part of this family I really appreciate
it I love you guys uh I wish you all the
best with your trading and your coding
and I'll speak with you in the next
lesson as I said links to this script
will be below take care