[Matplotlib-users] plt scale x-axis by constant factor f

Discussion:

Christian Jorgensen

2015-03-09 17:38:37 UTC

How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?

In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.

Best

Sterling Smith

2015-03-09 17:51:59 UTC

Permalink

Christian,

It sounds like you want to rescale your x axis values before plotting or use the x axis formatter. For the latter see
http://matplotlib.org/examples/pylab_examples/major_minor_demo1.html
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html

-Sterling

Post by Christian Jorgensen
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
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Benjamin Root

2015-03-09 17:52:20 UTC

Permalink

Ok, this really should be simple (and I am sure it is), but I cannot, for
the life of me, find the appropriate documentation for it. We need better
documentation about how to utilize the offset-text feature of tickers. It
can be either a multiple offset or an additive offset.

In any case, I know there is a better way to do this, but here is a
quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html

Cheers!
Ben Root

Post by Christian Jorgensen
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
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Christian Jorgensen

2015-03-09 17:57:56 UTC

Permalink

Post by Benjamin Root
Ok, this really should be simple (and I am sure it is), but I cannot, for
the life of me, find the appropriate documentation for it. We need better
documentation about how to utilize the offset-text feature of tickers. It
can be either a multiple offset or an additive offset.
In any case, I know there is a better way to do this, but here is a
quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root

Post by Christian Jorgensen
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
------------------------------------------------------------------------------
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Benjamin Root

2015-03-09 18:03:29 UTC

Permalink

I am not sure I understand. I took your question as "how do I make my x
tick labels show values as [0, 300] when my values really are [0, 3000]?".
Are the indexes you speak of ranging from 0 to 3000? If so, I don't see how
our examples aren't sufficient. As for formatting x "because it is not
defined", what is not defined? The formatting or x?

My array does not have an explicit x-coordinate

representation. The x-coordinate is simply the index.
print(array)
[ 0 0 20 ..., 8 8 8]
Thus what I would like is to adjoin the element
index as another row, how is this possible?
I cannot format x because it is not explicitly defined.

Post by Benjamin Root
Ok, this really should be simple (and I am sure it is), but I cannot,
for the life of me, find the appropriate documentation for it. We need
better documentation about how to utilize the offset-text feature of
tickers. It can be either a multiple offset or an additive offset.
In any case, I know there is a better way to do this, but here is a
quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root

Post by Christian Jorgensen
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
------------------------------------------------------------------------------
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Christian Jorgensen

2015-03-09 18:12:18 UTC

Permalink

My array is called D.dtrajs[0]

I'm plotting it as

plt.plot(D.dtrajs[0])
plt.ylabel('O2-Fe distance')
plt.xlabel('Frame')

There is thus no x-variable defined to
scale or modify. How would you do this?

Post by Christian Jorgensen

Post by Benjamin Root
I am not sure I understand. I took your question as "how do I make my x
tick labels show values as [0, 300] when my values really are [0, 3000]?".
Are the indexes you speak of ranging from 0 to 3000? If so, I don't see how
our examples aren't sufficient. As for formatting x "because it is not
defined", what is not defined? The formatting or x?

My array does not have an explicit x-coordinate

Post by Benjamin Root
Ok, this really should be simple (and I am sure it is), but I cannot,
for the life of me, find the appropriate documentation for it. We need
better documentation about how to utilize the offset-text feature of
tickers. It can be either a multiple offset or an additive offset.
In any case, I know there is a better way to do this, but here is a
quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
On Mon, Mar 9, 2015 at 1:38 PM, Christian Jorgensen <

Post by Christian Jorgensen
How can I scale my x-axis [0,3000] for the data to now
correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
------------------------------------------------------------------------------
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hub for all
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blogs to
news, videos, case studies, tutorials and more. Take a look and join the
conversation now. http://goparallel.sourceforge.net/
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Sterling Smith

2015-03-09 18:11:43 UTC

Permalink

Christian,

To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)

-Sterling

My array does not have an explicit x-coordinate
representation. The x-coordinate is simply the index.
print(array)
[ 0 0 20 ..., 8 8 8]
Thus what I would like is to adjoin the element
index as another row, how is this possible?
I cannot format x because it is not explicitly defined.
Ok, this really should be simple (and I am sure it is), but I cannot, for the life of me, find the appropriate documentation for it. We need better documentation about how to utilize the offset-text feature of tickers. It can be either a multiple offset or an additive offset.
In any case, I know there is a better way to do this, but here is a quick-n-dirty example that can get you where you want. Just modify the formatter used by the tickers to report the value as divided by 10.
http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best
------------------------------------------------------------------------------
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by Intel and developed in partnership with Slashdot Media, is your hub for all
things parallel software development, from weekly thought leadership blogs to
news, videos, case studies, tutorials and more. Take a look and join the
conversation now. http://goparallel.sourceforge.net/
_______________________________________________
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Sterling Smith

2015-03-09 18:13:16 UTC

Permalink

That was untested. It should start with (still untested)

x = array(range(len(array))

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

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Benjamin Root

2015-03-09 18:16:20 UTC

Permalink

Or just do this:

formatter = FuncFormatter(lambda x, pos: "%d" % x/10)
fig, ax = plt.subplots()ax.yaxis.set_major_formatter(formatter)plt.plot(D.dtrajs[0])
plt.ylabel('O2-Fe distance')
plt.xlabel('Frame')
plt.show()

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

for the life of me, find the appropriate documentation for it. We need
better documentation about how to utilize the offset-text feature of
tickers. It can be either a multiple offset or an additive offset.

In any case, I know there is a better way to do this, but here is a

quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.

http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
How can I scale my x-axis [0,3000] for the data to now correspond/show up
as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best

------------------------------------------------------------------------------

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sponsored

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blogs to

news, videos, case studies, tutorials and more. Take a look and join the
conversation now. http://goparallel.sourceforge.net/
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Christian Jorgensen

2015-03-09 18:35:00 UTC

Permalink

Thanks,

I ran Benjamin's code but it doesn't display the
figure anymore. It only prints a text about the figure

formatter = FuncFormatter(lambda x, pos: "%d" % x/10)

fig, ax = plt.subplots()

ax.yaxis.set_major_formatter(formatter)

plt.plot(D.dtrajs[0])

plt.ylabel('O2-Fe distance')

plt.xlabel('Frame')

plt.show()

<matplotlib.figure.Figure at 0x11b1f2090>

Post by Benjamin Root
formatter = FuncFormatter(lambda x, pos: "%d" % x/10)
fig, ax = plt.subplots()ax.yaxis.set_major_formatter(formatter)plt.plot(D.dtrajs[0])
plt.ylabel('O2-Fe distance')
plt.xlabel('Frame')
plt.show()

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

In any case, I know there is a better way to do this, but here is a

quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.

http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
How can I scale my x-axis [0,3000] for the data to now correspond/show

as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot seem
to find the command to do this with matplotlib.
Best

------------------------------------------------------------------------------

Dive into the World of Parallel Programming The Go Parallel Website,

sponsored

by Intel and developed in partnership with Slashdot Media, is your hub

for all

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Christian JÃžrgensen

Christian Jorgensen

2015-03-09 18:40:38 UTC

Permalink

Sterling,

this doesn't work, as it's using the array as a function

x = D.dtrajs[0](range(len(D.dtrajs[0])))

plt.plot(D.dtrajs[0])

plt.ylabel('O2-Fe distance')

plt.xlabel('Frame')

---------------------------------------------------------------------------TypeError
Traceback (most recent call
last)<ipython-input-147-8bbee6b254c1> in <module>()----> 1 x =
D.dtrajs[0](range(len(D.dtrajs[0]))) 2 plt.plot(D.dtrajs[0])
3 plt.ylabel('O2-Fe distance') 4 plt.xlabel('Frame')
TypeError: 'numpy.ndarray' object is not callable

Post by Christian Jorgensen
Thanks,
I ran Benjamin's code but it doesn't display the
figure anymore. It only prints a text about the figure
formatter = FuncFormatter(lambda x, pos: "%d" % x/10)
fig, ax = plt.subplots()
ax.yaxis.set_major_formatter(formatter)
plt.plot(D.dtrajs[0])
plt.ylabel('O2-Fe distance')
plt.xlabel('Frame')
plt.show()
<matplotlib.figure.Figure at 0x11b1f2090>

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

In any case, I know there is a better way to do this, but here is a

quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.

http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
On Mon, Mar 9, 2015 at 1:38 PM, Christian Jorgensen<
How can I scale my x-axis [0,3000] for the data to now correspond/show

as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot

seem

to find the command to do this with matplotlib.
Best

------------------------------------------------------------------------------

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Christian Jorgensen

2015-03-09 18:49:06 UTC

Permalink

I want to thank the users for their invaluable help.

My final error concerns the plotting:

<ipython-input-157-043a2bfb8704> in <lambda>(x, pos)----> 1 formatter
= FuncFormatter(lambda x, pos: "%d" % x/10) 2 3 fig, ax =
plt.subplots() 4 ax.yaxis.set_major_formatter(formatter) 5
a= plt.plot(D.dtrajs[0])
TypeError: unsupported operand type(s) for /: 'str' and 'int'

Post by Christian Jorgensen
Sterling,
this doesn't work, as it's using the array as a function
x = D.dtrajs[0](range(len(D.dtrajs[0])))
plt.plot(D.dtrajs[0])
plt.ylabel('O2-Fe distance')
plt.xlabel('Frame')
---------------------------------------------------------------------------TypeError Traceback (most recent call last)<ipython-input-147-8bbee6b254c1> in <module>()----> 1 x = D.dtrajs[0](range(len(D.dtrajs[0]))) 2 plt.plot(D.dtrajs[0]) 3 plt.ylabel('O2-Fe distance') 4 plt.xlabel('Frame')
TypeError: 'numpy.ndarray' object is not callable

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

In any case, I know there is a better way to do this, but here is a

quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.

http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
On Mon, Mar 9, 2015 at 1:38 PM, Christian Jorgensen<
How can I scale my x-axis [0,3000] for the data to now

correspond/show up

as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot

seem

to find the command to do this with matplotlib.
Best

------------------------------------------------------------------------------

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Benjamin Root

2015-03-09 18:57:24 UTC

Permalink

You might need to put parentheses around the statement for the lambda...

formatter = FuncFormatter(lambda x, pos: ("%d" % x/10))

Also, a tweak to my code. Change most of the "plt" to "ax" and use the
appropriate methods. I suspect that the ipython session you are in is
messing up the pyplot state machine and so being explicit for which axes
object you are operating on can prevent those blank plots.

ax.plot(D.dtrajs[0])

ax.set_ylabel('O2-Fe distance')

ax.set_xlabel('Frame')

plt.show()

Cheers!
Ben Root

Post by Christian Jorgensen
I want to thank the users for their invaluable help.
<ipython-input-157-043a2bfb8704> in <lambda>(x, pos)----> 1 formatter = FuncFormatter(lambda x, pos: "%d" % x/10) 2 3 fig, ax = plt.subplots() 4 ax.yaxis.set_major_formatter(formatter) 5 a= plt.plot(D.dtrajs[0])
TypeError: unsupported operand type(s) for /: 'str' and 'int'

Post by Sterling Smith
Christian,
To define your x coordinate, try
x = range(len(array))
x = x/10.
plot(x,array)
-Sterling

cannot, for the life of me, find the appropriate documentation for it. We
need better documentation about how to utilize the offset-text feature of
tickers. It can be either a multiple offset or an additive offset.

In any case, I know there is a better way to do this, but here is a

quick-n-dirty example that can get you where you want. Just modify the
formatter used by the tickers to report the value as divided by 10.

http://matplotlib.org/examples/pylab_examples/custom_ticker1.html
Cheers!
Ben Root
On Mon, Mar 9, 2015 at 1:38 PM, Christian Jorgensen<
How can I scale my x-axis [0,3000] for the data to now

correspond/show up

as [0, 300]?
In xmgrace, this is done with a linear transformation, but I cannot

seem

to find the command to do this with matplotlib.
Best

------------------------------------------------------------------------------

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