Public Data Access Overview / Discussion Forum

HI
I have many IDs and I want to do task 9 for them ; But I want to have one curve(average curve) instead of a lot curves in my chart . But I can't make average from my curves...

for example , for part type Gas , I want to get median from all the points in each snapshot , and then connect all the points of the average .
I can do this for one snapshot! As shown in the following code(for example for two IDs):

ids = [109974,110822]
list1 = []

for id in ids:
    url = "http://www.illustris-project.org/api/Illustris-1/snapshots/68/subhalos/" + str(id)
    sub = get(url) # get json response of subhalo properties

    # prepare dict to hold result arrays
    fields = ['snap','id','mass_gas']
    r = {}
    for field in fields:
        r[field] = []

    while sub['desc_sfid'] != -1:
        for field in fields:
            r[field].append(sub[field])
            # request the full subhalo details of the descendant by following the sublink URL
        sub = get(sub['related']['sublink_descendant'])

    # make a plot (notice our subhalo falls into a much more massive halo around snapshot 105)
    for partType in ['gas']:
        mass_logmsun = np.log10( np.array(r['mass_'+partType][1])*1e10/0.704)
        list1.append(mass_logmsun)

Sum = sum(list1) 
ave = Sum/2
plt.plot(r['snap'][1],ave,'.',label=partType)

But I can't generalize it to all the snapshots...
(I want to create a circle (loop) that does this for all the snapshots).

Thank you for your help.

Hi Maryam,

I'd suggest you review something like a numpy tutorial which should be helpful later. I would do something more like

num_snaps = 100
ids = [109974,110822]

mass_vs_time = np.zeros( (len(ids),num_snaps), dtype='float32')

for i, id in enumerate(ids):
    # download data for this subhalo
    mass_vs_time[i,:] = gas_mass_history

avg_mass_vs_time = np.mean(mass_vs_time, axis=0)

Thank you so much Dylan . You help me a lot .Thank you again .

Hi again Dylan ,

If I want to get the standard deviation diagram for the mean diagram I drew using the above code ,can you help me?
I have used the following code in continuation of the above code :

total_bins = 10
bins = np.linspace(68, 134 , total_bins)
delta = bins[1]-bins[0]
idx  = np.digitize(x,bins)
running_median = [np.median(avg_mass_vs_time[idx==k]) for k in range(total_bins)]
plt.plot(bins-delta/2 , running_median, color= 'blue' , lw=2  , markersize=1 )

running_std    = [avg_mass_vs_time[idx==k].std()/np.sqrt(len(avg_mass_vs_time[idx==k])) for k in range(total_bins)]
plt.errorbar(bins-delta/2,running_median,running_std,color='blue', lw=2.0 , marker='o', markersize=4, ls='none', mew=1)

But I think it is not true...

Thanks in advance for your help.

Hi Maryam,

The numpy std() function also has an axis argument, you can maybe use it in the same way. Beyond this I'm afraid I can't help with such detailed aspects.

I understand. Thank you very much for your guidance and for spend your time to help .Thank you so much .