To calculate the phase for each peak at each z, we first transformed the experimental m/z by multiplying by z/1.0033. In this space, each isotope peak is exactly 1 apart when z matches the true charge state. To calculate the phase, we simply extract the decimal part of the rescaled m/z by taking the value modulo 1 to yield a phase between 0 and 1. Because m/z is continuously sampled, we need to bin these phase values. The bin was calculated by multiplying the phase by the total number of bins and taking the floor of the value.