The numpy polynomial fit function for masked arrays, ma.polyfit, crashes on integer iput:
import numpy.ma as ma
x = ma.arange(2)
y = ma.arange(2)
p1 = ma.polyfit(np.float32(x), y, deg=1)
p2 = ma.polyfit( x , y, deg=1)
The last line results in an error:
ValueError: data type <type 'numpy.int64'> not inexact
Why can't I fit data with integer x-values (it's no problem with the normal numpy.polyfit function), is this a (known) bug?
It is indeed a bug from numpy.ma : the rcond (a parameter to exclude some values ) takes len(x)*np.finfo(x.dtypes).eps as a default value, and np.int32 does not have any epsfield (because an int does not have a relative precision).
import numpy.ma as ma
eps = np.finfo(np.float32).eps
x = ma.arange(2)
y = ma.arange(2)
p1 = ma.polyfit(np.float32(x), y, deg=1, rcond = len(x)*eps)
p2 = ma.polyfit( x , y, deg=1, rcond = len(x)*eps)
I've looked quickly into numpy's issues, and this bug does not seems to figured there. It might be a good idea to raise a new issue : New Issue
Related
I am building machine learning models for a certain data set. Then, based on the constraints and bounds for the outputs and inputs, I am trying to find the input parameters for the most minimized answer.
The problem which I am facing is that, when the model is a linear regression model or something like lasso, the minimization works perfectly fine.
However, when the model is "Decision Tree", it constantly returns the very initial value that is given to it. So basically, it does not enforce the constraints.
import numpy as np
import pandas as pd
from scipy.optimize import minimize
I am using the very first sample from the input data set for the optimization. As it is only one sample, I need to reshape it to (1,-1) as well.
x = df_in.iloc[0,:]
x = np.array(x)
x = x.reshape(1,-1)
This is my Objective function:
def objective(x):
x = np.array(x)
x = x.reshape(1,-1)
y = 0
for n in range(df_out.shape[1]):
y = Model[n].predict(x)
Y = y[0]
return Y
Here I am defining the bounds of inputs:
range_max = pd.DataFrame(range_max)
range_min = pd.DataFrame(range_min)
B_max=[]
B_min =[]
for i in range(range_max.shape[0]):
b_max = range_max.iloc[i]
b_min = range_min.iloc[i]
B_max.append(b_max)
B_min.append(b_min)
B_max = pd.DataFrame(B_max)
B_min = pd.DataFrame(B_min)
bnds = pd.concat([B_min, B_max], axis=1)
These are my constraints:
con_min = pd.DataFrame(c_min)
con_max = pd.DataFrame(c_max)
Here I am defining the constraint function:
def const(x):
x = np.array(x)
x = x.reshape(1,-1)
Y = []
for n in range(df_out.shape[1]):
y = Model[n].predict(x)[0]
Y.append(y)
Y = pd.DataFrame(Y)
a4 =[]
for k in range(Y.shape[0]):
a1 = Y.iloc[k,0] - con_min.iloc[k,0]
a2 = con_max.iloc[k, 0] - Y.iloc[k,0]
a3 = [a2,a1]
a4 = np.concatenate([a4, a3])
return a4
c = const(x)
con = {'type': 'ineq', 'fun': const}
This is where I try to minimize. I do not pick a method as the automatically picked model has worked so far.
sol = minimize(fun = objective, x0=x,constraints=con, bounds=bnds)
So the actual constraints are:
c_min = [0.20,1000]
c_max = [0.3,1600]
and the max and min range for the boundaries are:
range_max = [285,200,8,85,0.04,1.6,10,3.5,20,-5]
range_min = [215,170,-1,60,0,1,6,2.5,16,-18]
I think you should check the output of 'sol'. At times, the algorithm is not able to perform line search completely. To check for this, you should check message associated with 'sol'. In such a case, the optimizer returns initial parameters itself. There may be various reasons of this behavior. In a nutshell, please check the output of sol and act accordingly.
Arad,
If you have not yet resolved your issue, try using scipy.optimize.differential_evolution instead of scipy.optimize.minimize. I ran into similar issues, particularly with decision trees because of their step-like behavior resulting in infinite gradients.
I have two question:
1) I'd like to know how can I add/subtract a constante torch.FloatTensor of size 1 to all of the elemets of a torch.FloatTensor of size 30.
2) How can I multiply each element of a torch.FloatTensor of size 30 by a random value (different or not for each).
My code:
import torch
dtype = torch.cuda.FloatTensor
def main():
pop, xmax, xmin = 30, 5, -5
x = (xmax-xmin)*torch.rand(pop).type(dtype)+xmin
y = torch.pow(x, 2)
[miny, indexmin] = y.min(0)
gxbest = x[indexmin]
pxbest = x
pybest = y
v = torch.rand(pop)
vnext = torch.rand()*v + torch.rand()*(pxbest - x) + torch.rand()*(gxbest - x)
main()
What is the best way to do it? I think I should so how convert the gxbest into a torch.FloatTensor of size 30 but how can I do that?
I've try to create a vector:
Variable(torch.from_numpy(np.ones(pop)))*gxbest
But it did not work. The multiplication is not working also.
RuntimeError: inconsistent tensor size
Thank you all for your help!
1) How can I add/subtract a constant torch.FloatTensor of size 1 to all of the elements of a torch.FloatTensor of size 30?
You can do it directly in pytorch 0.2.
import torch
a = torch.randn(30)
b = torch.randn(1)
print(a-b)
In case if you get any error due to size mismatch, you can make a small change as follows.
print(a-b.expand(a.size(0))) # to make both a and b tensor of same shape
2) How can I multiply each element of a torch.FloatTensor of size 30 by a random value (different or not for each)?
In pytorch 0.2, you can do it directly as well.
import torch
a = torch.randn(30)
b = torch.randn(1)
print(a*b)
In case, if you get an error due to size mismatch, do as follows.
print(a*b.expand(a.size(0)))
So, in your case you can simply change the size of gxbest tensor from 1 to 30 as follows.
gxbest = gxbest.expand(30)
Let x and y be vectors of length N, and z is a function z = f(x,y). In Tensorflow v1.0.0, tf.hessians(z,x) and tf.hessians(z,y) both returns an N by N matrix, which is what I expected.
However, when I concatenate the x and y into a vector p of size 2*N using tf.concat, and run tf.hessian(z, p), it returns error "ValueError: None values not supported."
I understand this is because in the computation graph x,y ->z and x,y -> p, so there is no gradient between p and z. To circumvent the problem, I can create p first, slice it into x and y, but I will have to change a ton of my code. Is there a more elegant way?
related question: Slice of a variable returns gradient None
import tensorflow as tf
import numpy as np
N = 2
A = tf.Variable(np.random.rand(N,N).astype(np.float32))
B = tf.Variable(np.random.rand(N,N).astype(np.float32))
x = tf.Variable(tf.random_normal([N]) )
y = tf.Variable(tf.random_normal([N]) )
#reshape to N by 1
x_1 = tf.reshape(x,[N,1])
y_1 = tf.reshape(y,[N,1])
#concat x and y to form a vector with length of 2*N
p = tf.concat([x,y],axis = 0)
#define the function
z = 0.5*tf.matmul(tf.matmul(tf.transpose(x_1), A), x_1) + 0.5*tf.matmul(tf.matmul(tf.transpose(y_1), B), y_1) + 100
#works , hx and hy are both N by N matrix
hx = tf.hessians(z,x)
hy = tf.hessians(z,y)
#this gives error "ValueError: None values not supported."
#expecting a matrix of size 2*N by 2*N
hp = tf.hessians(z,p)
Compute the hessian by its definition.
gxy = tf.gradients(z, [x, y])
gp = tf.concat([gxy[0], gxy[1]], axis=0)
hp = []
for i in range(2*N):
hp.append(tf.gradients(gp[i], [x, y]))
Because tf.gradients computes the sum of (dy/dx), so when computing the second partial derivative, one should slice the vector into scalars and then compute the gradient. Tested on tf1.0 and python2.
Strange error from numpy via matplotlib when trying to get a histogram of a tiny toy dataset. I'm just not sure how to interpret the error, which makes it hard to see what to do next.
Didn't find much related, though this nltk question and this gdsCAD question are superficially similar.
I intend the debugging info at bottom to be more helpful than the driver code, but if I've missed something, please ask. This is reproducible as part of an existing test suite.
if n > 1:
return diff(a[slice1]-a[slice2], n-1, axis=axis)
else:
> return a[slice1]-a[slice2]
E TypeError: ufunc 'subtract' did not contain a loop with signature matching types dtype('<U1') dtype('<U1') dtype('<U1')
../py2.7.11-venv/lib/python2.7/site-packages/numpy/lib/function_base.py:1567: TypeError
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> entering PDB >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
> py2.7.11-venv/lib/python2.7/site-packages/numpy/lib/function_base.py(1567)diff()
-> return a[slice1]-a[slice2]
(Pdb) bt
[...]
py2.7.11-venv/lib/python2.7/site-packages/matplotlib/axes/_axes.py(5678)hist()
-> m, bins = np.histogram(x[i], bins, weights=w[i], **hist_kwargs)
py2.7.11-venv/lib/python2.7/site-packages/numpy/lib/function_base.py(606)histogram()
-> if (np.diff(bins) < 0).any():
> py2.7.11-venv/lib/python2.7/site-packages/numpy/lib/function_base.py(1567)diff()
-> return a[slice1]-a[slice2]
(Pdb) p numpy.__version__
'1.11.0'
(Pdb) p matplotlib.__version__
'1.4.3'
(Pdb) a
a = [u'A' u'B' u'C' u'D' u'E']
n = 1
axis = -1
(Pdb) p slice1
(slice(1, None, None),)
(Pdb) p slice2
(slice(None, -1, None),)
(Pdb)
I got the same error, but in my case I am subtracting dict.key from dict.value. I have fixed this by subtracting dict.value for corresponding key from other dict.value.
cosine_sim = cosine_similarity(e_b-e_a, w-e_c)
here I got error because e_b, e_a and e_c are embedding vector for word a,b,c respectively. I didn't know that 'w' is string, when I sought out w is string then I fix this by following line:
cosine_sim = cosine_similarity(e_b-e_a, word_to_vec_map[w]-e_c)
Instead of subtracting dict.key, now I have subtracted corresponding value for key
I had a similar issue where an integer in a row of a DataFrame I was iterating over was of type numpy.int64. I got the
TypeError: ufunc 'subtract' did not contain a loop with signature matching types dtype('<U1') dtype('<U1') dtype('<U1')
error when trying to subtract a float from it.
The easiest fix for me was to convert the row using pd.to_numeric(row).
Why is it applying diff to an array of strings.
I get an error at the same point, though with a different message
In [23]: a=np.array([u'A' u'B' u'C' u'D' u'E'])
In [24]: np.diff(a)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-24-9d5a62fc3ff0> in <module>()
----> 1 np.diff(a)
C:\Users\paul\AppData\Local\Enthought\Canopy\User\lib\site-packages\numpy\lib\function_base.pyc in diff(a, n, axis)
1112 return diff(a[slice1]-a[slice2], n-1, axis=axis)
1113 else:
-> 1114 return a[slice1]-a[slice2]
1115
1116
TypeError: unsupported operand type(s) for -: 'numpy.ndarray' and 'numpy.ndarray'
Is this a array the bins parameter? What does the docs say bins should be?
I am fairly new to this myself, but I had a similar error and found that it is due to a type casting issue. I was trying to concatenate rather than take the difference but I think the principle is the same here. I provided a similar answer on another question so I hope that is OK.
In essence you need to use a different data type cast, in my case I needed str not float, I suspect yours is the same so my suggested solution is. I am sorry I cannot test it before suggesting but I am unclear from your example what you were doing.
return diff(str(a[slice1])-str(a[slice2]), n-1, axis=axis)
Please see my example code below for the fix to my code, the change occurs on the third to last line. The code is to produce a basic random forest model.
import scipy
import math
import numpy as np
import pandas as pd
from sklearn.ensemble import RandomForestRegressor
from sklearn import preprocessing, metrics, cross_validation
Data = pd.read_csv("Free_Energy_exp.csv", sep=",")
Data = Data.fillna(Data.mean()) # replace the NA values with the mean of the descriptor
header = Data.columns.values # Ues the column headers as the descriptor labels
Data.head()
test_name = "Test.csv"
npArray = np.array(Data)
print header.shape
npheader = np.array(header[1:-1])
print("Array shape X = %d, Y = %d " % (npArray.shape))
datax, datay = npArray.shape
names = npArray[:,0]
X = npArray[:,1:-1].astype(float)
y = npArray[:,-1] .astype(float)
X = preprocessing.scale(X)
XTrain, XTest, yTrain, yTest = cross_validation.train_test_split(X,y, random_state=0)
# Predictions results initialised
RFpredictions = []
RF = RandomForestRegressor(n_estimators = 10, max_features = 5, max_depth = 5, random_state=0)
RF.fit(XTrain, yTrain) # Train the model
print("Training R2 = %5.2f" % RF.score(XTrain,yTrain))
RFpreds = RF.predict(XTest)
with open(test_name,'a') as fpred :
lenpredictions = len(RFpreds)
lentrue = yTest.shape[0]
if lenpredictions == lentrue :
fpred.write("Names/Label,, Prediction Random Forest,, True Value,\n")
for i in range(0,lenpredictions) :
fpred.write(RFpreds[i]+",,"+yTest[i]+",\n")
else :
print "ERROR - names, prediction and true value array size mismatch."
This leads to an error of;
Traceback (most recent call last):
File "min_example.py", line 40, in <module>
fpred.write(RFpreds[i]+",,"+yTest[i]+",\n")
TypeError: ufunc 'add' did not contain a loop with signature matching types dtype('S32') dtype('S32') dtype('S32')
The solution is to make each variable a str() type on the third to last line then write to file. No other changes to then code have been made from the above.
import scipy
import math
import numpy as np
import pandas as pd
from sklearn.ensemble import RandomForestRegressor
from sklearn import preprocessing, metrics, cross_validation
Data = pd.read_csv("Free_Energy_exp.csv", sep=",")
Data = Data.fillna(Data.mean()) # replace the NA values with the mean of the descriptor
header = Data.columns.values # Ues the column headers as the descriptor labels
Data.head()
test_name = "Test.csv"
npArray = np.array(Data)
print header.shape
npheader = np.array(header[1:-1])
print("Array shape X = %d, Y = %d " % (npArray.shape))
datax, datay = npArray.shape
names = npArray[:,0]
X = npArray[:,1:-1].astype(float)
y = npArray[:,-1] .astype(float)
X = preprocessing.scale(X)
XTrain, XTest, yTrain, yTest = cross_validation.train_test_split(X,y, random_state=0)
# Predictions results initialised
RFpredictions = []
RF = RandomForestRegressor(n_estimators = 10, max_features = 5, max_depth = 5, random_state=0)
RF.fit(XTrain, yTrain) # Train the model
print("Training R2 = %5.2f" % RF.score(XTrain,yTrain))
RFpreds = RF.predict(XTest)
with open(test_name,'a') as fpred :
lenpredictions = len(RFpreds)
lentrue = yTest.shape[0]
if lenpredictions == lentrue :
fpred.write("Names/Label,, Prediction Random Forest,, True Value,\n")
for i in range(0,lenpredictions) :
fpred.write(str(RFpreds[i])+",,"+str(yTest[i])+",\n")
else :
print "ERROR - names, prediction and true value array size mismatch."
These examples are from a larger code so I hope the examples are clear enough.
I think #James is right. I got stuck by same error while working on Polyval(). And yeah solution is to use the same type of variabes. You can use typecast to cast all variables in the same type.
BELOW IS A EXAMPLE CODE
import numpy
P = numpy.array(input().split(), float)
x = float(input())
print(numpy.polyval(P,x))
here I used float as an output type. so even the user inputs the INT value (whole number). the final answer will be typecasted to float.
I ran into the same issue, but in my case it was just a Python list instead of a Numpy array used. Using two Numpy arrays solved the issue for me.
I'm trying to calculate the average Luminance of an RGB image. To do this, I find the luminance of each pixel i.e.
L(r,g,b) = X*r + Y*g + Z*b (some linear combination).
And then find the average by summing up luminance of all pixels and dividing by width*height.
To speed this up, I'm using pyopencl.reduction.ReductionKernel
The array I pass to it is a Single Dimension Numpy Array so it works just like the example given.
import Image
import numpy as np
im = Image.open('image_00000001.bmp')
data = np.asarray(im).reshape(-1) # so data is a single dimension list
# data.dtype is uint8, data.shape is (w*h*3, )
I want to incorporate the following code from the example into it . i.e. I would make changes to datatype and the type of arrays I'm passing. This is the example:
a = pyopencl.array.arange(queue, 400, dtype=numpy.float32)
b = pyopencl.array.arange(queue, 400, dtype=numpy.float32)
krnl = ReductionKernel(ctx, numpy.float32, neutral="0",
reduce_expr="a+b", map_expr="x[i]*y[i]",
arguments="__global float *x, __global float *y")
my_dot_prod = krnl(a, b).get()
Except, my map_expr will work on each pixel and convert each pixel to its luminance value.
And reduce expr remains the same.
The problem is, it works on each element in the array, and I need it to work on each pixel which is 3 consecutive elements at a time (RGB ).
One solution is to have three different arrays, one for R, one for G and one for B ,which would work, but is there another way ?
Edit: I changed the program to illustrate the char4 usage instead of float4:
import numpy as np
import pyopencl as cl
import pyopencl.array as cl_array
deviceID = 0
platformID = 0
workGroup=(1,1)
N = 10
testData = np.zeros(N, dtype=cl_array.vec.char4)
dev = cl.get_platforms()[platformID].get_devices()[deviceID]
ctx = cl.Context([dev])
queue = cl.CommandQueue(ctx)
mf = cl.mem_flags
Data_In = cl.Buffer(ctx, mf.READ_WRITE, testData.nbytes)
prg = cl.Program(ctx, """
__kernel void Pack_Cmplx( __global char4* Data_In, int N)
{
int gid = get_global_id(0);
//Data_In[gid] = 1; // This would change all components to one
Data_In[gid].x = 1; // changing single component
Data_In[gid].y = 2;
Data_In[gid].z = 3;
Data_In[gid].w = 4;
}
""").build()
prg.Pack_Cmplx(queue, (N,1), workGroup, Data_In, np.int32(N))
cl.enqueue_copy(queue, testData, Data_In)
print testData
I hope it helps.