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From: C M <cmpython@gm...>  20110127 21:37:44

> just make a numpy array out of your two lists, and you'll be able > to subtract one from the other. > > import numpy as np > top = np.array(top) > bot = np.array(bot) Thank you, Paul. That worked and I'm now able to display bar charts. I appreciate it. Best, Che 
From: C M <cmpython@gm...>  20110126 22:41:46

I usually do this for line graphs with markers: line, = self.subplot.plot_date(dates,data) along with some keywords to tweak the plot. I then add line to a dictionary to keep track of it: self.line_to_data_dict[line] = self.activity But today I tried this with a bar chart, just changing plot_date to bar and renaming the "line," to "bars,": fake_data = [2,2,5] bars, = self.subplot.bar(fake_data, fake_data ) This gave me the error: ValueError: too many values to unpack. OK, so if I removed the comma from "bars," so it is just "bars", it goes through but then I cannot add it to my dictionaryI get: > TypeError: list objects are unhashable Help in understanding this and a better approach would be helpful. Thanks, Che 
From: Benjamin Root <ben.root@ou...>  20110127 00:49:22

On Wednesday, January 26, 2011, C M <cmpython@...> wrote: > I usually do this for line graphs with markers: > > line, = self.subplot.plot_date(dates,data) > > along with some keywords to tweak the plot. I then add line to a > dictionary to keep track of it: > > self.line_to_data_dict[line] = self.activity > > But today I tried this with a bar chart, just changing plot_date to > bar and renaming the "line," to "bars,": > > fake_data = [2,2,5] > bars, = self.subplot.bar(fake_data, fake_data ) > > This gave me the error: ValueError: too many values to unpack. > > OK, so if I removed the comma from "bars," so it is just "bars", it > goes through but then I cannot add it to my dictionaryI get: > >> TypeError: list objects are unhashable > > Help in understanding this and a better approach would be helpful. Thanks, > Che > Just a thought, are you trying out the new legend code? Could you do a print of the type for bars? Ben Root 
From: C M <cmpython@gm...>  20110127 01:08:06

> Just a thought, are you trying out the new legend code? I don't know if I am or not. But these problems are prior to any code regarding the legend. > Could you do a print of the type for bars? When I write it as just bars without the comma it is: bars type = <type 'list'> If I write it with the comma ( bars,) then it won't even run because of the ValueError. I know the 2nd problem is that a dictionary cannot have a mutable object like a list as a key. But previously, as I said, I was able to call line, (with the comma) and it would work. In fact, line, with a comma gives this type: line type = <class 'matplotlib.lines.Line2D'> Thanks, Che 
From: JaeJoon Lee <lee.joon@gm...>  20110127 02:17:10

On Thu, Jan 27, 2011 at 10:07 AM, C M <cmpython@...> wrote: > I know the 2nd problem is that a dictionary cannot have a mutable > object like a list as a key. But previously, as I said, I was able to > call line, (with the comma) and it would work. In fact, line, with a > comma gives this type: > If you just want a hashable object, can you just cast it to a tuple? bars = self.subplot.bar(fake_data, fake_data ) bars_tuple = tuple(bars) bars_tuple can be used as a dictionary key. Regards, JJ 
From: C M <cmpython@gm...>  20110127 06:34:12

On Wed, Jan 26, 2011 at 9:16 PM, JaeJoon Lee <lee.j.joon@...> wrote: > On Thu, Jan 27, 2011 at 10:07 AM, C M <cmpython@...> wrote: >> I know the 2nd problem is that a dictionary cannot have a mutable >> object like a list as a key. But previously, as I said, I was able to >> call line, (with the comma) and it would work. In fact, line, with a >> comma gives this type: >> > > If you just want a hashable object, can you just cast it to a tuple? > > > bars = self.subplot.bar(fake_data, fake_data ) > bars_tuple = tuple(bars) > > bars_tuple can be used as a dictionary key. Yes, that can work, thanks, but I am still stuck without a bar chart for other reasons (see point #3 below), and I am still confused. I have some questions that if answered can hopefully help me get clearer: 1) What does the comma do exactly? If I put this: "line," I create a matplotlib line object, whereas if I put just "line" I create a list. Does this mean that plot() in mpl returns a tuple that contains one element, which is a mpl line object? (If so, why doesn't it just return the line object itself?) 2) Why does line, followed by plot() return a mpl line object but bars, followed by bar() not return some kind of matplotlib object (like a line)? Why does it instead give the "ValueError: Too many values to unpack" error? 3) I am getting just hammered with the following error *a lot* in date plotting lately: ValueError: ordinal must be >= 1 And I can't figure out what sorts of mistakes or situations are triggering it. More of the traceback above that error is at the end of this message. Does someone know when this error will be thrown when using dates so I can at least know what to check for in my data? Thanks, Che  more of Traceback: for ylabel_i in self.subplot.get_yticklabels(): File "C:\Python25\lib\sitepackages\matplotlib\axes.py", line 2646, in get_yticklabels self.yaxis.get_ticklabels(minor=minor)) File "C:\Python25\lib\sitepackages\matplotlib\axis.py", line 1087, in get_ticklabels return self.get_majorticklabels() File "C:\Python25\lib\sitepackages\matplotlib\axis.py", line 1071, in get_majorticklabels ticks = self.get_major_ticks() File "C:\Python25\lib\sitepackages\matplotlib\axis.py", line 1169, in get_major_ticks numticks = len(self.get_major_locator()()) File "C:\Python25\lib\sitepackages\matplotlib\dates.py", line 743, in __call__ self.refresh() File "C:\Python25\lib\sitepackages\matplotlib\dates.py", line 752, in refresh dmin, dmax = self.viewlim_to_dt() File "C:\Python25\lib\sitepackages\matplotlib\dates.py", line 524, in viewlim_to_dt return num2date(vmin, self.tz), num2date(vmax, self.tz) File "C:\Python25\lib\sitepackages\matplotlib\dates.py", line 289, in num2date if not cbook.iterable(x): return _from_ordinalf(x, tz) File "C:\Python25\lib\sitepackages\matplotlib\dates.py", line 203, in _from_ordinalf dt = datetime.datetime.fromordinal(ix) ValueError: ordinal must be >= 1 
From: C M <cmpython@gm...>  20110127 07:04:09

> 3) I am getting just hammered with the following error *a lot* in date > plotting lately: > > ValueError: ordinal must be >= 1 OK, I made up a small runnable sample to show this with bar(). (Using code that someone else wrote[1]). This code runs when using plot_date(), but if you comment that out and comment in the ax.bar() line, it will give this ValueError. import matplotlib.pyplot as plt import matplotlib as mpl import numpy as np import datetime as dt # Make a series of events 1 day apart x = mpl.dates.drange(dt.datetime(2009,10,1), dt.datetime(2010,1,15), dt.timedelta(days=1)) # Vary the datetimes so that they occur at random times # Remember, 1.0 is equivalent to 1 day in this case... x += np.random.random(x.size) # We can extract the time by using a modulo 1, and adding an arbitrary base date times = x % 1 + int(x[0]) # (The int is so the yaxis starts at midnight...) # I'm just plotting points here, but you could just as easily use a bar. fig = plt.figure() ax = fig.add_subplot(111) #comment out: ax.plot_date(x, times, 'ro') #comment in #ax.bar(x, times) ax.yaxis_date() fig.autofmt_xdate() plt.show() [1]http://stackoverflow.com/questions/4790265/plottimeofdayvsdateinmatplotlib 
From: Paul Ivanov <pivanov314@gm...>  20110127 07:55:04
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C M, on 20110127 02:03, wrote: > > 3) I am getting just hammered with the following error *a lot* in date > > plotting lately: > > > > ValueError: ordinal must be >= 1 > > > OK, I made up a small runnable sample to show this with bar(). (Using > code that someone else wrote[1]). This code runs when using > plot_date(), but if you comment that out and comment in the ax.bar() > line, it will give this ValueError. > > > import matplotlib.pyplot as plt > import matplotlib as mpl > import numpy as np > import datetime as dt > > # Make a series of events 1 day apart > x = mpl.dates.drange(dt.datetime(2009,10,1), > dt.datetime(2010,1,15), > dt.timedelta(days=1)) > # Vary the datetimes so that they occur at random times > # Remember, 1.0 is equivalent to 1 day in this case... > x += np.random.random(x.size) > > # We can extract the time by using a modulo 1, and adding an arbitrary base date > times = x % 1 + int(x[0]) # (The int is so the yaxis starts at midnight...) > > # I'm just plotting points here, but you could just as easily use a bar. > fig = plt.figure() > ax = fig.add_subplot(111) > > #comment out: > ax.plot_date(x, times, 'ro') > Hi C. M., The reason you were getting that error is because unless you specify otherwise, ax.bar will make the bottom of the bars at 0  which isn't an allowed date, hence the error. Change your bar line to this (I also added align='center', but you can remove it if you want): > #comment in bot = times.min().round() ax.bar(x, timesbot, bottom=bot, align='center') > > ax.yaxis_date() > fig.autofmt_xdate() > > plt.show() best,  Paul Ivanov 314 address only used for lists, offlist direct email at: http://pirsquared.org  GPG/PGP key id: 0x0F3E28F7 
From: C M <cmpython@gm...>  20110127 18:57:02

Hi Paul, > The reason you were getting that error is because unless you > specify otherwise, ax.bar will make the bottom of the bars at 0  > which isn't an allowed date, hence the error. Change your bar > line to this (I also added align='center', but you can remove it > if you want): Aha, OK that makes sense. Thank you. I think the point #3 in my previous email about the "Ordinal must be >= 1" has all been about what is or isn't allowed as a proper date. So your example worked of course, but I am still not able to get my real code to plot a bar chart. If I tell you what the format of the data is, maybe you can help me. I would like to plot dates (on x axis) versus time intervals (on y). I have a list of dates and I have a two lists (self.data[0] and self.data[1]), one of the start times ("bots") and one of the stop times ("tops"). But when I go to plot it, and do this (based on your code...for now leaving out the round() step): bots = self.data[0] tops = self.data[1] bars = self.subplot.bar(self.final_dates, topbot, bottom=bot, align='center') I get the error: TypeError: unsupported operand type(s) for : 'list' and 'list' Because I am trying to subtract the "bots" list from the "tops" list. In the example code I gave, bot and times were not lists but were a 'numpy.ndarray' and a numpy.float64' object, respectfully, and I guess the  operand can be used on them. How can I structure my data such that this can work? (For some reason I have not had nearly this much confusion with plotting lines, just bars). Thanks for all the help, Che (CM) 
From: Paul Ivanov <pivanov314@gm...>  20110127 19:33:44
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C M, on 20110127 13:56, wrote: > bars = self.subplot.bar(self.final_dates, topbot, bottom=bot, align='center') > > I get the error: > > TypeError: unsupported operand type(s) for : 'list' and 'list' > > Because I am trying to subtract the "bots" list from the "tops" list. > In the example code I gave, bot and times were not lists but were a > 'numpy.ndarray' and a numpy.float64' object, respectfully, and I guess > the  operand can be used on them. > > How can I structure my data such that this can work? (For some reason > I have not had nearly this much confusion with plotting lines, just > bars). Che, just make a numpy array out of your two lists, and you'll be able to subtract one from the other. import numpy as np top = np.array(top) bot = np.array(bot) best,  Paul Ivanov 314 address only used for lists, offlist direct email at: http://pirsquared.org  GPG/PGP key id: 0x0F3E28F7 
From: C M <cmpython@gm...>  20110127 21:37:44

> just make a numpy array out of your two lists, and you'll be able > to subtract one from the other. > > import numpy as np > top = np.array(top) > bot = np.array(bot) Thank you, Paul. That worked and I'm now able to display bar charts. I appreciate it. Best, Che 
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